CN201436786U - Testing system of temperature frequency correction device - Google Patents
- ️Wed Apr 07 2010
Embodiment
Below in conjunction with Figure of description embodiment of the present utility model is described.
An embodiment of the temperature frequency correcting apparatus that provides 100 in the utility model is provided Fig. 1.Described temperature frequency correcting apparatus comprises that 100 comprise
crystal oscillator110,
temperature induction unit120,
memory cell130 and frequency lock unit 140.In an instantiation, the integrated circuit (IC) chip of described temperature
frequency correcting apparatus100 for being packaged as a whole, promptly each unit in it is encapsulated as one.Described
crystal oscillator110 can generate reference frequency f R, described reference frequency f RCan be the simulated clock simulation clock signal, also can be dagital clock signal, and it can the occurrence frequency drift with variation of temperature.Described
temperature induction unit120 is used to respond to the internal temperature of described temperature
frequency correcting apparatus100, because temperature induction unit and
crystal oscillator110 are integrated into one, so the internal temperature of
temperature induction unit120 inductions can reflect the temperature of crystal oscillator substantially.Described
memory cell130 is used for storing temperature frequency correction control data, and described temperature and frequency correcting control data obtains through further processing after temperature frequency is measured by described temperature
frequency correcting apparatus100 is carried out, and hereinafter will specifically introduce.Described
frequency lock unit140 can be used for generating the desired output frequency f that compensates through temperature frequency based on described reference frequency signal, frequency control word (frequency control word is called for short FCW) and temperature and frequency correcting control data OUT, described frequency control word can be imported by the outside.
Fig. 2 is the functional-block diagram of an embodiment of the
frequency lock unit200 in the utility model, and described
frequency lock unit200 can be an embodiment of the frequency lock unit among Fig. 1.Described
frequency lock unit200 comprises frequency
locking synthesis unit210,
frequency correction unit230 and temperature and frequency correcting word generation unit 250.Described temperature and frequency correcting
word generation unit250 is used to generate corresponding temperature and frequency correcting word (the tempereture frequency correction word of Current Temperatures T (internal temperature of the temperature frequency correcting apparatus that also can described temperature induction unit provides) of input, be called for short TCW), this temperature and frequency correcting word TCW can be to the reference frequency f under the Current Temperatures T RTemperature frequency drift compensate/proofread and correct.Described
frequency correction unit230 is used to utilize the temperature and frequency correcting word TCW of acquisition to frequency control word (frequency control word, be called for short FCW) proofread and correct/compensate to obtain emending frequency control word (corrected frequency control word is called for short FCW_new).Described frequency
locking synthesis unit110 is used for reference frequency f RFor the basis generates the desired output frequency f according to emending frequency control word FCW_new OUTIt should be noted that in addition, described Current Temperatures T, temperature and frequency correcting word TCW, frequency control word FCW and emending frequency control word FCW_new are digital signals, (such as 32,16 or 8 the binary sequence) that they are normally represented by binary sequence.
In one embodiment, described frequency
locking synthesis unit210 generates the desired output frequency f according to following formula OUT:
f OUT＝K*FCW_new*f R
Wherein K represents proportionality coefficient, the output frequency signal f that can obtain expecting according to proportionality coefficient K and emending frequency control signal FCW_new OUT
In one embodiment, described
frequency correction unit230 generates emending frequency control word FCW_new according to following formula:
FCW_new＝FCW+TCW。
In one embodiment, such as the frequency signal of needs generation 890MHz, described frequency control word FCW can be the binary sequence of the described frequency values of expression, and described temperature and frequency correcting word TCW can be the described reference frequency f of expression RThe binary sequence of the frequency drift corrected value under Current Temperatures, the frequency signal of the 890MHz that obtains by emending frequency control word FCW_new just can not produce bigger frequency drift with variation of temperature like this, that is to say that the output frequency of 890MHz has obtained temperature-compensating.In another embodiment, described frequency control word FCW can change within the specific limits, and frequency control word FCW also can be used as frequency modulated signal to generate modulation output frequency f like this OUTSuch as, needs generate frequency modulation(FM) (Frequency Modulated) signal of 890MHz～910MHz frequency range, and described frequency control word FCW can be the binary sequence of the described frequency range of expression.
Fig. 4 shows reference frequency f RUncompensated temperature frequency characteristic curve, temperature frequency compensated curve and the characteristic example of temperature frequency after the compensation, wherein said uncompensated reference frequency has in-50 ℃ to 125 ℃ temperature ranges approximately ± frequency drift of 10ppm, and the frequency drift that the frequency drift of the output after the compensation does not more compensate output reduces greatly.As shown in Figure 4, drift compensates to temperature frequency if arbitrary temperature value (or temperature spot), just can utilize this frequency correction value all to the correspondent frequency corrected value should be arranged.Here the frequency correction value of mentioning is exactly described temperature and frequency correcting word TCW.
Please consult shown in Figure 2ly once more, described temperature and frequency correcting word generation unit 250 (also can be referred to as temperature and frequency correcting word deriving means) also includes
temperature comparing unit252,
temperature approaches unit256, temperature and frequency correcting letter
lock order unit254.
The described temperature and frequency correcting control data of the memory cell input from Fig. 1 includes the initial temperature correct word TCW (T0) of initial temperature T0 correspondence.Described
temperature comparing unit252 is Current Temperatures T and current accounting temperature Tx relatively; At comparative result is that current accounting temperature point Tx is not when being in the lock-in range of Current Temperatures T, described temperature and frequency correcting letter
lock order unit254 utilize the temperature and frequency correcting word TCW (Tx) of current accounting temperature point Tx correspondence calculate convergence Current Temperatures T next accounting temperature point (such as: if T＞Tx, then next accounting temperature point is Tx+S; If T＜Tx, then next accounting temperature point is Tx-S, described S is the predetermined temperature interval) corresponding temperature and frequency correcting word, described
temperature approaches unit256 is exported to
temperature comparing unit252 with next accounting temperature point of convergence Current Temperatures as current accounting temperature point Tx and is proceeded comparison; At comparative result is current accounting temperature point Tx when being in the lock-in range of Current Temperatures T, and described temperature and frequency correcting letter
lock order unit254 obtains the temperature and frequency correcting word TCW (T) of Current Temperatures T correspondence according to the temperature and frequency correcting word TCW (Tx) of current accounting temperature point Tx correspondence.The initial value of described current accounting temperature point Tx is initial temperature T0, and the first duration of the temperature and frequency correcting word of current accounting temperature point Tx correspondence is initial temperature frequency correction word TCW (T0).
Like this, in the utility model, do not need all to store corresponding temperature and frequency correcting word for each temperature spot, the temperature and frequency correcting word that only needs the storing initial temperature adopts the successive approximation computing just can calculate the temperature and frequency correcting word TCW (T) of Current Temperatures T correspondence afterwards.
In a concrete example, the lock-in range of described Current Temperatures T can be in the predetermined temperature range that comprises Current Temperatures T.In addition, the lock-in range that described accounting temperature Tx is not in Current Temperatures T also bag can comprise two kinds of situations, and promptly described accounting temperature Tx is not in the lock-in range of Current Temperatures T and T and is not in the lock-in range of Current Temperatures T and T less than Tx greater than Tx and described accounting temperature Tx.For instance, T＞Tx+S can represent that described accounting temperature Tx is not in lock-in range and T greater than Tx, T＜Tx can represent that described accounting temperature Tx is not in lock-in range and T less than Tx, and Tx≤T＜Tx+S can represent that described accounting temperature Tx is in lock-in range.Again for instance, T＞Tx+S can represent that described accounting temperature Tx is not in lock-in range and T greater than Tx, T＜Tx-S can represent that described accounting temperature Tx is not in lock-in range and T less than Tx, and Tx-S＜T＜Tx+S can represent that described accounting temperature Tx is in lock-in range.
In a concrete enforcement, described temperature and frequency correcting control data also stores fixed step size and fixed step size symbol table, described fixed step size and described fixed step size symbol table can be the digital signals of being represented by binary sequence, store sign bit (the sign bit of the fixed step size of each discrete temperature spot correspondence in the described fixed step size symbol table, be called for short SB), just can represent that such as 10 can represent to bear.Described discrete temperature spot is meant to have the predetermined temperature temperature spot of S at interval, the described predetermined temperature size of S at interval can be chosen as required and can different values be set at different Applicable temperature scopes, can be 0.2 ℃ a temperature range such as S.This predetermined temperature interval S has reflected the temperature covering precision of fixed step size symbol table, has just reflected the temperature covering precision in the temperature frequency compensation in the utility model.Give fixed step size with the symbol of each sign bit in the described fixed step size symbol table and just can obtain actual step size: SB (Tx) *Fixed step size, wherein SB (Tx) can represent the sign bit of the fixed step size symbol table of temperature spot Tx correspondence.Wherein initial temperature frequency correction word TCW (T0), fixed step size and fixed step size symbol table can be by in the memory cell among data signal line importing Fig. 1.
In a concrete example, at comparative result is current accounting temperature point Tx when not being in lock-in range and T greater than Tx, and described temperature and frequency correcting letter
lock order unit254 obtains the sign bit that current accounting temperature point Tx approaches the needed fixed step size of next accounting temperature point Tx+S (such as being sign bit in the fixed step size symbol table of current accounting temperature point Tx correspondence) from the fixed step size symbol table, give fixed step size with the sign bit that obtains and approach the needed actual step size of next accounting temperature point Tx+S to obtain current accounting temperature point Tx, utilize the temperature and frequency correcting word TCW (Tx) of current accounting temperature point Tx correspondence and the temperature and frequency correcting word TCW (Tx+S) that actual step size obtains next accounting temperature point Tx+S correspondence.At comparative result is that accounting temperature Tx is not when being in lock-in range and T less than Tx, described temperature and frequency correcting letter
lock order unit254 obtains the sign bit that current accounting temperature point Tx approaches the needed fixed step size of next accounting temperature point Tx-S (because Tx-S＜Tx can claim that also Tx-S is last accounting temperature point) (such as being sign bit in the fixed step size symbol table of next accounting temperature point Tx-S correspondence) from the fixed step size symbol table, give fixed step size with the sign bit that obtains and approach the needed actual step size of next accounting temperature point Tx-S to obtain current accounting temperature point Tx, utilize the temperature and frequency correcting word TCW (Tx) of current accounting temperature point Tx correspondence and the temperature and frequency correcting word TCW (Tx-S) that actual step size obtains next accounting temperature point Tx-S correspondence.
As can be seen in an example of the present utility model, for a discrete temperature spot, described fixed step size symbol table only need be stored the sign bit of 1 bit binary data as the fixed step size of this temperature spot correspondence, thereby makes the data volume of described fixed step size symbol table become very little.Simultaneously, also can in the fixed step size symbol table, store the sign bit of more temperature spots, promptly can decrement keep predetermined temperature interval S smaller, can improve the precision of temperature frequency compensation like this.In the utility model by adopting a kind of digital desired temperature and frequency correcting value of frequency drift that interpolation method automatically locks different temperature spots of approaching one by one, thereby reduce the temperature and frequency correcting value of required storage to greatest extent, also improved simultaneously the precision of temperature frequency compensation, and determine that by digitized control able to programme reference clock source (as quartz crystal or other oscillator) at different performance or electronic system require the minimal hardware compensation scheme of required employing to frequency stability, have also reduced the cost and the performance requirement in system reference clock source in addition to greatest extent.
Fig. 3 shows the flow chart of an embodiment of the temperature and frequency correcting word acquisition methods in the utility model, and it has also reflected the course of work of described temperature and frequency correcting
word generation unit250.
301, Tx=T0, TCW (Tx)=TCW (T0).
Tx represents current accounting temperature point, and its initial value is initial temperature T0; The temperature and frequency correcting word of the current accounting temperature point Tx correspondence of TCW (Tx) expression, its initial value is initial temperature frequency correction word TCW (T0).
303 reads digital temperature value T, i.e. the Current Temperatures that provides of the temperature induction unit of mentioning in the preamble.
305, relatively Current Temperatures T and accounting temperature Tx when accounting temperature Tx is not in the lock-in range of Current Temperatures T and T greater than Tx, change
step307 over to; When accounting temperature Tx is not in the lock-in range of Current Temperatures T and T less than Tx, change
step313 over to; When accounting temperature Tx is in the lock-in range of Current Temperatures T, change
step319 over to.
307 reads the sign bit SB (Tx) in the fixed step size symbol table of Current Temperatures point Tx correspondence, and gives the actual step size that fixed step size forms Current Temperatures point Tx correspondence with this symbol.
The value of described sign bit or be 1, or be 0, represent positive and negative respectively.
Step 309 utilizes the actual step size of the temperature and frequency correcting word TCW (Tx) of current accounting temperature point Tx and Current Temperatures point Tx correspondence to ask for the temperature and frequency correcting word TCW (Tx+S) of next accounting temperature point Tx+S correspondence.
311, Tx=Tx+S in addition, and return step 303.Here why will turn back to 303, and not turn back to 305, be because described digital temperature T may change in computational process.
313 reads the sign bit SB (Tx-S) in the fixed step size symbol table of a temperature spot Tx-S correspondence, and gives the actual step size that fixed step size forms a last temperature spot Tx-S correspondence with this symbol.
Step 315 utilizes the temperature and frequency correcting word TCW (Tx) of current accounting temperature point Tx and the actual step size of a last temperature spot Tx-S correspondence to ask for the corresponding temperature and frequency correcting word TCW (Tx-S) of an accounting temperature point.
317, Tx=Tx-S in addition, and return step 303.Equally, why will turn back to 303 here, and not turn back to 305, be because described digital temperature T may change in computational process.
319, if this moment, current accounting temperature point Tx equaled described digital temperature T, the TCW (Tx) that then will calculate gained is as the temperature and frequency correcting word TCW output of calculating gained; Otherwise, utilize TCW (Tx) interpolation to obtain TCW (T) and its temperature and frequency correcting word TCW output as the calculating gained.
Need explain, if the temperature sense precision of described temperature induction unit (precision of Current Temperatures T) is less than the temperature covering precision of described fixed step size symbol table, temperature sense precision such as described digital temperature sensor is 0.1 ℃, and the covering temperature accuracy of described fixed step size symbol table is 0.2 ℃ (being that S equals 0.2 ℃), will occur that accounting temperature Tx is in the lock-in range of Current Temperatures T and the situation that is not equal to Current Temperatures T needs just can obtain TCW (T) through interpolation.Yet, if the temperature sense precision of described temperature induction unit is smaller or equal to the temperature covering precision of described fixed step size symbol table, accounting temperature Tx is in lock-in range and just is meant Tx=T so, like this after accounting temperature Tx is in lock-in range, described temperature and frequency correcting word TCW (Tx) is exactly the temperature and frequency correcting word TCW of Current Temperatures T correspondence, has therefore carried out interpolation arithmetic with regard to not needing.In addition, when the needs interpolation just can be obtained TCW (T), can adopt various interpolation methods, such as linear interpolation, non-linear interpolation, parabola interpolation etc., interpolation also may need near temperature and frequency correcting word such as TCW (Tx-S), TCW (Tx+S) in general except needs temperature and frequency correcting word TCW (Tx).
Calculate the temperature and frequency correcting word TCW of gained in output after,, enter
step321 afterwards with Tlock=T.
Step 321 reads digital temperature value T.
Step 323 judges whether described digital temperature value T equals described Tlock, if, then return
step321 and continue to read digital temperature value, otherwise return
step305, continue to repeat above-mentioned locking process.
By carrying out above-mentioned steps, the temperature and frequency correcting word that calculates Current Temperatures T correspondence that described temperature and frequency correcting
word generation unit250 utilizes TCW (T0), fixed step size and fixed step size symbol table to approach one by one quickly and accurately.For the temperature and frequency correcting word of each temperature spot, only need storage 1 bit sign data in the utility model, this has significantly reduced memory data output.In addition, owing to only need store 1 bit data for each temperature spot, so the data that can store more temperature spots, the precision of frequency-temperature compensation has also increased greatly like this.
In a specific embodiment, in the described memory cell 130 among Fig. 1 except storing initial temperature frequency correction word TCW (T0), fixed step size and fixed step size symbol table, also store the difference TCWd (T0) of initial temperature frequency correction word TCW (T0), the difference TCWd of wherein said temperature and frequency correcting word is meant the difference of the temperature and frequency correcting word of adjacent temperature spot correspondence, fixed step size is then represented the absolute difference of difference of the temperature and frequency correcting word of adjacent temperature spot correspondence, this moment, it can be represented with TCWds, also can be referred to as the difference fixed step size this moment in addition.Described initial temperature point T0 can for the minimum of temperature coverage (such as-30 ℃ to 50 ℃) such as-30 ℃.Store the sign bit SB of the fixed step size of each discrete temperature spot correspondence in the described fixed step size symbol table, the figure place of the binary sequence of described fixed step size symbol table depends on its temperature coverage and predetermined temperature S at interval, such as the temperature coverage is from-30 to 50 ℃, S is 0.2 ℃, the binary sequence that then needs (50-(30))/0.2-1=400-1 position is not (because maximum temperature point has next temperature spot for 50 ℃, therefore do not need to store the symbol of the corresponding fixed step size of this maximum temperature point, therefore can lack 1 bit data).It should be noted that TCW (T0), TCWd (T0), TCWds and fixed step size symbol table are interior by the memory cell 130 of data wire importing, as for how measuring these data will be described in more detail below.
Fig. 5 is the schematic flow sheet according to the temperature and frequency correcting word acquisition methods of above-mentioned specific embodiment.
See also shown in Figure 5ly, the computational methods of temperature and frequency correcting word TCW comprise the steps.
Step 501, initialization Tx, TCW (Tx), TCWd (Tx).
Tx represents current accounting temperature point, the temperature and frequency correcting word of TCW (Tx) expression accounting temperature point Tx correspondence, the difference of the temperature and frequency correcting word of TCWd (Tx) expression accounting temperature point Tx correspondence.Described initialization can be in addition:
Tx＝T0；TCW(Tx)＝TCW(T0)；TCWd(Tx)＝TCWd(T0)。
Step 503 reads digital temperature value T, is exactly that preamble is mentioned Current Temperatures or target temperature.
Step 505 judges that whether described digital temperature T value is more than or equal to Tx+S, if change step 507 over to; Otherwise change step 513 over to.
Step 507 reads the sign bit SB (Tx) in the fixed step size symbol table of current accounting temperature point Tx correspondence, gives the actual step size that TCWds forms Current Temperatures point Tx correspondence: SB (Tx) with this symbol *TCWds.This sign bit or be 1, or be 0, wherein 1 expression just, 0 expression is negative.
Step 509 is asked for the difference TCWd (Tx+S) of the temperature and frequency correcting word of the temperature and frequency correcting word TCW (Tx+S) of next accounting temperature point Tx+S correspondence and next accounting temperature point Tx+S correspondence.
TCW (Tx+S)=TCW (Tx)+TCWd (Tx) wherein;
TCWd(Tx+S)＝TCWd(Tx)+SB(Tx) ＊TCWds；
This process of asking for the correlation of next accounting temperature point can be called as forward direction and proofread and correct.
Step 511, Tx=Tx+S in addition, and return step 503.Here why will turn back to 503, and not turn back to 505, be because described digital temperature T may change in computational process.
Step 513 continues to judge that whether described digital temperature T is less than Tx.If then change step 515 over to; Otherwise, change step 521 over to.
Step 515 reads the sign bit SB (Tx-S) in the fixed step size symbol table of an accounting temperature point Tx-S correspondence, gives the actual step size that TCWds forms a last accounting temperature point Tx-S correspondence: SB (Tx-S) with this symbol *TCWds.
Step 517, the difference TCWd (Tx-S) that asks for the temperature and frequency correcting word of an accounting temperature point Tx-S correspondence reaches the temperature and frequency correcting word TCW (Tx-S) of a last accounting temperature point Tx-S correspondence.
TCWd (Tx-S)=TCWd (Tx)-SB (Tx-S) wherein *TCWds
TCW(Tx-S)＝TCW(Tx)-TCWd(Tx-S)，
Proofread and correct with respect to foregoing forward direction, the correlation of asking for an accounting temperature point here gets process and can be called as the back to correction.
Step 519, Tx=Tx-S in addition, and return step 503.Equally, why will turn back to 503 here, and not turn back to 505, be because described digital temperature T may change in computational process.
Step 521, if this moment, current accounting temperature point Tx equaled described digital temperature T, the TCW (Tx) that then will calculate gained is as the temperature and frequency correcting word TCW output of calculating gained; If Tx+S＞T＞Tx then utilizes TCW (Tx) and TCW (Tx+S) interpolation to obtain TCW (T) and it is as the temperature and frequency correcting word TCW output of calculating gained.
Calculate the temperature and frequency correcting word TCW of gained in output after,, enter step 523 afterwards with Tlock=T.
Step 523 reads digital temperature value T.
Step 525 judges whether described digital temperature value T equals described Tlock, if, then return step 523 and continue to read digital temperature value, otherwise return step 505, continue to repeat above-mentioned locking process.
For instance, when described initial temperature T0 is temperature coverage minimum-30 ℃, when each temperature
frequency correcting apparatus100 as shown in Figure 1 comes into operation, described temperature induction unit can provide Current Temperatures T, such as T is 20 ℃, so flow process can continuous repeating step 503-511 to allow the Tx value approach 20 ℃ from-30 ℃ fast, enter step 513 afterwards until last locking temperature T.Along with the locking of Tx, also can obtain the temperature and frequency correcting word of Tx correspondence.During the unexpected change of temperature in use, such as unexpected decline, flow process can reenter the tracking locking process, and promptly repeating step 503,505,513-519 step enter step 521 with locking temperature T afterwards to allow Tx approach new T value fast at once.
As seen characteristics of the acquisition methods of the temperature and frequency correcting word in the utility model, advantage is: utilize initial temperature frequency correction word, the difference of initial temperature frequency correction word starts trace flow, constantly utilize the corresponding temperature and frequency correcting word of current accounting temperature point, the difference of temperature and frequency correcting word, sign bit in the fixed step size symbol table and fixed step size calculate the temperature and frequency correcting word of correspondence of next accounting temperature point of convergence target temperature, be locked to Current Temperatures point T until the accounting temperature point, carry out trying to achieve the temperature and frequency correcting word of Current Temperatures point T correspondence according to interpolation.
Below, introduce the measuring process of TCW (T0), TCWd (T0), TCWds and fixed step size symbol table in detail once.Fig. 6 is the functional-block diagram of an embodiment of the measuring system of the temperature frequency correcting apparatus in the utility model.Described measuring
system600 comprises
sweat box610, be contained in temperature frequency correcting apparatus to be measured 620 in the sweat box,
tape deck630,
match device640,
sampling apparatus650 and
calculation element660 again.
Described
sweat box610 can be used for regulating temperature in it in predetermined temperature range, and described predetermined temperature range can be-50 ℃-130 ℃.Described temperature frequency correcting apparatus to be measured 620 can be a temperature frequency correcting apparatus shown in Figure 1, described temperature
frequency correcting apparatus620 to be measured is positioned in the
sweat box610, afterwards can be from low to high, from high to low or the alternate manner temperature of regulating in the
sweat box610 make whole temperature range of its scanning.Because the variation of temperature in the
sweat box610, thereby cause the variation of the internal temperature (being the internal temperature of temperature induction unit induction in it) of temperature
frequency correcting apparatus620 to be measured, it should be noted that the internal temperature of temperature in the
sweat box610 and temperature frequency correcting apparatus to be measured 620 can be inconsistent.
Described
tape deck630 is used to write down desired output frequency values and the corresponding internal temperature values of described temperature frequency correcting apparatus to be measured under an internal temperature values, and an internal temperature values and corresponding desired output frequency values can be formed a temperature frequency measurement point.Concrete, at the fixed time such as in the 60s, the variation of the internal temperature values of described temperature induction unit induction less than the predetermined temperature change threshold such as 0.5 ℃, this internal temperature values and the described temperature frequency correcting apparatus desired output frequency values under this internal temperature values under the then described recording device records.Afterwards, regulate the temperature in the
sweat box610, described
tape deck630 is noted desired output frequency values and the corresponding internal temperature values of described temperature frequency correcting apparatus to be measured under another internal temperature values once more, so constantly carry out repetition abundant discrete internal temperature values and the desired output frequency values under the respective inner temperature value in noting whole temperature range, the interval between the described discrete internal temperature values is less than the predetermined temperature S at interval in the preamble.In a specific embodiment, also include frequency meter in the described
tape deck630, described frequency meter is used to read the numerical value of the desired output frequency of temperature frequency correcting apparatus to be measured.
Described
match device640 is used for simulating continuous temperature frequency curve according to each discrete internal temperature values and corresponding desired output frequency values.This can obtain by the whole bag of tricks of the prior art, but must will guarantee the temperature frequency curve and the actual reference frequency f of its generation RThe temperature frequency curve consistent as far as possible, and keep the level and smooth of curve.In one embodiment, when not having the temperature frequency sudden change, can adopt Beckman curve maker (Bechamann curve generator), just can generate more accurate temperature frequency characteristic curve by using a few temperature frequency test point.
Described sampling apparatus again 650 is used at interval the temperature frequency curve that simulates being sampled to obtain each sample temperature value frequency value corresponding again with predetermined sample temperature.Described predetermined sample temperature is the predetermined temperature interval S that mentions in the preamble at interval, and the value of described S will determine the temperature covering precision of described fixed step size symbol table, and choosing of described S can arbitrarily be set as required.In an example, described S value can be set different values at different temperature applicable ranges, such as using 0.1 ℃ as temperature sampling interval S at 0 ℃-20 ℃, uses 0.2 ℃ as temperature sampling interval S in other temperature range.
Why the utility model adopts
match device640 to reach
sampling apparatus650 again, be in order to make
tape deck630 measure and write down some temperature frequency measurement points as much as possible less, simultaneously can obtain abundant temperature frequency sample point again, so that the compensation of the temperature frequency in the utility model has enough precision.Described
tape deck630 every measurements and write down a temperature frequency measurement point and all need to spend certain hour, the temperature frequency measurement point too much will increase exponentially the measurement cost, by adopt
match device640 and again sampling
apparatus650 can be easy to obtain at double in or tenfold in the temperature frequency sample point of temperature frequency measurement point.Therefore, described predetermined sample temperature at interval S be generally less than or much smaller than the temperature interval of the internal temperature values of measuring.
Described calculation element is used for calculating the temperature and frequency correcting control data according to each sample temperature value and correspondent frequency value, and described temperature and frequency correcting control data is imported in the memory cell of described temperature frequency correcting apparatus.
Accordingly, Fig. 7 shows the schematic flow sheet of an embodiment of the method for measurement of the temperature frequency correcting apparatus in the utility model.
Step 701 writes down desired output frequency values and the corresponding internal temperature values of described temperature frequency correcting apparatus under each discrete internal temperature values.
At first need to write down desired output frequency values and corresponding internal temperature values under next internal temperature values, note desired output frequency values and corresponding internal temperature values under another internal temperature values afterwards again, so constantly repeat then to obtain desired output frequency values and corresponding internal temperature values under each discrete internal temperature values.Before this step, regulate the step of
sweat box610 variations in temperature in addition, adopt the variation of the internal temperature that can cause temperature frequency correcting apparatus like this.
Step 703 simulates continuous temperature frequency curve according to each discrete internal temperature values and corresponding desired output frequency values.
Step 705 is sampled to obtain each sample temperature value frequency value corresponding to the temperature frequency curve that simulates at interval with predetermined sample temperature again.
Step 707 calculates the temperature and frequency correcting control data according to each sample temperature value and correspondent frequency value.
Step 709 imports described temperature and frequency correcting control data in the memory cell of described temperature
frequency correcting apparatus620.
The detailed process that calculates the temperature and frequency correcting control data according to each sample temperature value and correspondent frequency value will specifically describe hereinafter, wherein comprise that with the temperature and frequency correcting control data difference TCWd (T0), the difference fixed step size TCWds of initial temperature frequency correction word TCW (T0), initial temperature frequency correction word and fixed step size symbol table are that example is introduced.Fig. 8 shows the TCW (T0) in the utility model, the computational process of TCWd (T0), TCWds, and Fig. 9 shows the computational process of the fixed step size symbol table in the utility model.
As shown in Figure 8, the computational methods of described TCW (T0), TCWd (T0), TCWds comprise the steps.
Step 801 according to the frequency values of each sample temperature point and the functional relation between the temperature and frequency correcting word, utilizes each sample temperature point frequency value corresponding to ask for the theoretical temperatures frequency correction word TCW of each sample temperature point Tx correspondence Ideal(Tx), wherein Tx represents to be spaced apart the discrete sampling temperature spot from min (Tx) to max (Tx) of S, and min (Tx) is the minimum value of Tx, and max (Tx) is the maximum of Tx.It should be noted that Tx represents current accounting temperature point in preamble, not exclusively the same with the physical meaning of representative herein, only need it is got final product as a parameter for the ease of understanding.Obtained the frequency values (output frequency that influenced by temperature frequency) of a sample temperature point, know the theoretical output frequency (i.e. the output frequency that not influenced by temperature frequency) of this sample temperature point before again, can obtain theoretical temperatures frequency correction word (promptly should carry out great temperature frequency compensation in theory) under this sample temperature point easily according between the two frequency-splitting.
The theoretical temperatures frequency correction word TCW of each sample temperature point Tx correspondence Ideal(Tx) will go on record and be used for determining the value of described each sign bit of fixed step size symbol table.
Step 803 is calculated the theoretical temperatures frequency correction word TCW of each sample temperature point Tx correspondence Ideal(Tx) difference TCWd Ideal(Tx), wherein
TCWd ideal(Tx)＝TCWd ideal(Tx+S)-TCWd ideal(Tx)，
Tx belongs to [min (Tx), max (Tx-S)] herein.
Step 805, a selected arbitrarily sample temperature is put pairing theoretical temperatures frequency correction word TCW Ideal(Tx) be previously described initial temperature frequency correction word TCW (T0), should put pairing theoretical temperatures frequency correction word TCW by selected sample temperature so Ideal(Tx) difference TCWd Ideal(Tx) will be registered as the difference TCWd (T0) of previously described initial temperature frequency correction word TCW (T0).Described selected sample temperature point is exactly described initial temperature T0, and it can be minimum, peak or the median of temperature coverage.
Step 807 is calculated the theoretical temperatures frequency correction word TCW of each sample temperature point Tx correspondence Ideal(Tx) difference TCWd Ideal(Tx) difference TCWdd Ideal(Tx), i.e. theoretical temperatures frequency correction word TCW Ideal(Tx) second differnce, wherein
TCWdd ideal(Tx)＝TCWd ideal(Tx+S)-TCWd ideal(Tx)，
Tx belongs to [min (Tx), max (Tx-2S)] herein.
Step 809 is with the theoretical temperatures frequency correction word TCW of each sample temperature point Tx correspondence Ideal(Tx) second differnce TCWdd Ideal(Tx) the absolute value maximum is recorded as previously described difference fixed step size TCWds in.Why choosing maximum is in order to guarantee that matched curve (curve that promptly utilizes each accounting temperature frequency correction word that the difference fixed step size calculates to form) can catch up with the variation of ideal curve (being the temperature frequency curve that obtains in the match device 640) for difference step size TCWds.Certainly in other embodiments, also can choose slightly little second differnce value is the difference fixed step size.
Hence one can see that, and just can calculate through execution in step 801-809 needs the initial temperature frequency correction word TCW (T0) that preserves, the difference TCWd (T0) and the difference step size TCWds of initial temperature frequency correction word in the described primary data memory cell.
Subsequently, can utilize the initial temperature frequency correction word TCW (T0) that has obtained, difference TCWd (T0), difference step size TCWds and the corresponding theoretical temperatures frequency correction word TCW of described each sample temperature point of initial temperature frequency correction word Ideal(Tx) calculate the value that obtains bits per inch certificate in the described fixed step size symbol table.Please referring to shown in Figure 9, the acquisition process of the value of each bit data is as follows in the described fixed step size symbol table.
901, initialization Tx, NTCW (Tx-S) and NTCWd (Tx-S).
Tx represents current sample temperature point, the temperature and frequency correcting word of NTCW (Tx-S) expression Tx-S temperature spot correspondence, the difference of the temperature and frequency correcting word of the temperature and frequency correcting word correspondence of NTCWd (Tx-S) expression Tx-S temperature spot correspondence.It should be noted that, the temperature and frequency correcting word NTCW (Tx-S) of Tx-S temperature spot correspondence is not described theoretical temperatures frequency correction word, but the temperature and frequency correcting word that comes out according to the Difference Calculation of initial temperature frequency correction word and initial temperature frequency correction word.
Suppose that at the described initial temperature T0 of preamble be the minimum that practical application covers temperature range, so described initialization is exactly:
Tx＝T0+S；NTCW(Tx-S)＝TCW(T0)；NTCWd(Tx-S)＝TCWd(T0)。
Here because initial temperature T0 is the minimum temperature value, the temperature spot Tx that therefore need ask for only need equal the value of the corresponding positions in the fixed step size symbol table that T0+S just can realize asking for each temperature spot correspondence.If initial temperature T0 is a peak, then need other Tx=T0-S, other parameter also needs according to the same rule corresponding modify.
Step 903 is calculated the temperature and frequency correcting word NTCW (Tx) of current sample temperature point Tx correspondence, is specially:
NTCW(Tx)＝NTCW(Tx-S)+NTCWd(Tx-S)。
Step 905 supposes that the value of sign bit SB (Tx-S) in the fixed step size symbol table of Tx-S temperature spot correspondence is 0, asks for the first accounting temperature frequency correction word NTCW0 (Tx+S) of Tx+S temperature spot correspondence, is specially:
NTCW0(Tx+S)＝NTCW(Tx)+NTCWd(Tx)
＝NTCW(Tx-S)+NTCWd(Tx-S)+NTCWd(Tx-S)+SB(Tx) ＊TCWds
＝NTCW(Tx-S)+2 ＊NTCWd(Tx-S)-TCWds。
907, first accounting temperature frequency correction word NTCW0 (Tx+S) that asks for Tx+S temperature spot correspondence and theoretical temperatures frequency correction word TCW Ideal(Tx+S) Cha the first absolute value DNTCW0 (Tx+S) is specially:
DNTCW0(Tx+S)＝Abs(TCW ideal(Tx+S)-NTCW0(Tx+S))。
Step 909 supposes that the value of sign bit SB (Tx-S) in the fixed step size symbol table of Tx-S temperature spot correspondence is 1, asks for the second accounting temperature frequency correction word NTCW1 (Tx+S) of Tx+S temperature spot correspondence, is specially:
NTCW1(Tx+S)＝NTCW(Tx-S)+2 ＊NTCWd(Tx-S)+SB(Tx-S) ＊TCWds
＝NTCW(Tx-S)+2 ＊NTCWd(Tx-S)+TCWds。
911, accounting temperature frequency correction word NTCW1 (Tx+S) that asks for Tx+S temperature spot correspondence and theoretical temperatures frequency correction word TCW Ideal(the second absolute value DNTCW1 (Tx+S) of Tx+S difference is specially:
DNTCW1(Tx+S)＝Abs(TCW ideal(Tx+S)-NTCW0(Tx+S))。
913, judge that described first absolute value whether less than described second absolute value, promptly judges whether:
DNTCW0 (Tx+S)＜DNTCW1 (Tx+S) if then enter
step915, otherwise enters
step917.
915, the value of sign bit SB (Tx-S) is 0 in the fixed step size symbol table of judgement Tx-S temperature spot correspondence, and enters
step919.
917, the value of sign bit SB (Tx-S) is 1 in the fixed step size symbol table of judgement Tx-S temperature spot correspondence, and enters step 921.
919, the difference NTCWd (Tx) of the temperature and frequency correcting word of calculating Tx temperature spot correspondence, promptly
NTCWd(Tx)＝NTCWd(Tx-S)-TCWds。
Step 921, the difference NTCWd (Tx) of the temperature and frequency correcting word of calculating Tx temperature spot correspondence, promptly
NTCWd(Tx)＝NTCWd(Tx-S)+TCWds。
923, Tx=Tx+S in addition.
Step 925 judges that Tx whether smaller or equal to MAX (Tx)-S, if not, then finishes calculation process, otherwise returns
step903, repeats above-mentioned steps.
Carry out above-mentioned steps 901-925, just can calculate the value of each data in the described fixed step size symbol table.
At last just can be with the initial temperature frequency correction word TCW (T0) that calculates, difference TCWd (T0), the difference step size TCWds of initial temperature frequency correction word and the fixed step size symbol table imports described temperature frequency correcting apparatus by data wire memory cell.
In another specific embodiment, in the memory cell of described temperature frequency correcting apparatus except storing initial temperature frequency correction word TCW (T0), fixed step size and fixed step size symbol table, also store the difference TCWd (T0) of initial temperature frequency correction word TCW (T0), the second differnce TCWdd (T0) of initial temperature frequency correction word TCW (T0), the difference TCWd of wherein said temperature and frequency correcting word is meant the difference of the temperature and frequency correcting word of adjacent temperature spot correspondence, the second differnce TCWdd of described temperature and frequency correcting word is meant the difference of difference of the temperature and frequency correcting word of adjacent temperature spot correspondence, fixed step size is then represented the difference of second differnce of the temperature and frequency correcting word of adjacent temperature spot correspondence, this moment, it can be represented with TCWdds, and also can be referred to as the second differnce fixed step size this moment.In this embodiment, the computational process of obtaining of temperature and frequency correcting word TCW can mainly be that step 509 and 517 is understood some variation with reference to computational process shown in Figure 5, and wherein step 509 becomes:
TCW(Tx+S)＝TCW(Tx)+TCWd(Tx)
TCWd(Tx+S)＝TCWd(Tx)+TCWdd(Tx)
TCWdd(Tx+S)＝TCWdd(Tx)+SB(Tx) ＊TCWdds，
Wherein step 517 becomes:
TCWdd(Tx-S)＝TCWdd(Tx)-SB(Tx-S) ＊TCWdds
TCWd(Tx-S)＝TCWd(Tx)-TCWdd(Tx-S)
TCW(Tx-S)＝TCW(Tx)-TCWd(Tx-S)
Similarly, some variations also can take place in the difference TCWd (T0) of initial temperature frequency correction word TCW (T0), initial temperature frequency correction word TCW (T0), second differnce TCWdd (T0), the second differnce fixed step size TCWdds of initial temperature frequency correction word TCW (T0) and the measuring process of fixed step size symbol table, but principle is identical with previous examples, just repeats no more here.Certainly, other are executed and also may use the above difference in three rank or three rank in the example, and principle is all similar, holds and does not give unnecessary details.
In another specific embodiment, only store initial temperature frequency correction word TCW (T0), fixed step size and fixed step size symbol table in the memory cell of described temperature frequency correcting apparatus, described fixed step size table is then represented the difference of the temperature and frequency correcting word of adjacent temperature spot correspondence, and this moment, it can be represented with TCWs.In this embodiment, the computational process of temperature and frequency correcting word TCW can mainly be that step 509 and 517 is understood some variation with reference to computational process shown in Figure 5, and wherein step 509 becomes:
TCW(Tx+S)＝TCW(Tx)+SB(Tx) ＊TCWs
Wherein step 517 becomes:
TCW(Tx-S)＝TCW(Tx)-SB(Tx-S) ＊TCWs。
Similarly, some variations also can take place in the measuring process of initial temperature frequency correction word TCW (T0), fixed step size TCWs and fixed step size symbol table, but principle is identical with previous examples, just repeats no more here.
In sum, characteristics of the scheme of obtaining of temperature and frequency correcting word of the present utility model, advantage or progressive being: be not the temperature and frequency correcting word (such as 32 bit data) of as of the prior art, storing each temperature spot correspondence, but only store symbol (1 bit data) and one or a few fixed step size and the initial temperature frequency correction word of the fixed step size of each temperature spot correspondence, when needs obtain the temperature and frequency correcting word of Current Temperatures correspondence, sign bit according to the fixed step size of each temperature spot correspondence, the temperature and frequency correcting word of fixed step size and last computation (initial value is an initial temperature frequency correction word) calculates one by one and levels off to the temperature and frequency correcting word of Current Temperatures, is locked in the temperature and frequency correcting word of Current Temperatures until result of calculation.
The above only is preferred embodiment of the present utility model, and is in order to restriction the utility model, not all within spirit of the present utility model and principle, any modification of being done, is equal to replacement etc., all should be included within the protection range of the present utility model.