Thread: Post disappeared - censored?


Permlink Replies: 4 - Pages: 1 - Last Post: Aug 2, 2011 8:39 PM Last Post By: ze Threads: [ Previous | Next ]
ze

Posts: 3
Registered: 04/28/08
Post disappeared - censored?
Posted: Aug 2, 2011 3:54 PM
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I had posted a question about long time that it takes for the 53132A counters to give a reading after a 100:1 change in frequency, got an initial reply, then posted another comment/question. The thread apparently was deleted at that point, instead of any further discussion.

Was there any forum rule violated? Why was it deleted? Topic was "Long time to complete measurement after frequency change".

Has this forum turned into a marketing tool? I now keep getting unsolicited sales pitches with the topic in the subject, like the ones below. Unsubscribe doesn't seem to help.

Your Agilent 53132A inquiry: Use Agilent scope probes/adapters with your counter
Your Agilent 53132A inquiry: Get counter/timer measurement tips
Your Agilent 53132A inquiry: Make fast, precise frequency measurements
lhornburg

Posts: 475
Registered: 01/15/10
Re: Post disappeared - censored?
Posted: Aug 2, 2011 4:56 PM   in response to: ze in response to: ze
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Not sure why it was deleted but I'll look into it. Our goal is for this not to turn into a marketing forum but a useful way for customer to get help. I'll see what I can do.
lhornburg

Posts: 475
Registered: 01/15/10
Re: Post disappeared - censored?
Posted: Aug 2, 2011 4:58 PM   in response to: ze in response to: ze
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How are these being delivered to you:

Your Agilent 53132A inquiry: Use Agilent scope probes/adapters with your counter
Your Agilent 53132A inquiry: Get counter/timer measurement tips
Your Agilent 53132A inquiry: Make fast, precise frequency measurements

I don't see them on the forum???

Are you getting promotional emails?
iandoubleyou


Posts: 60
Registered: 02/07/07
Re: Post disappeared - censored?
Posted: Aug 2, 2011 5:21 PM   in response to: ze in response to: ze
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Hi Guys - this post should definitely not have been removed. I have found it on our forums backup and clearly it should not have been touched - my apologies.

Ze - if you would like to re post - please do - if not - please see the question and the follow up replies below. Regarding the emails you are receiving - these are not related to the forum. The only time we will use the email address you registered with is to announce any major changes related to the forum or how you access it. If you can send an example of the email to Luke or me - we will follow up to find the source.

Ze - Long time to complete measurement after frequency change
53132A, power up condition except for no auto-trigger, 1s gate, 50R termination. Incoming signal, to show the issue, is FSK, hopping between 80MHz and 800kHz every 10s.
Expectation would be of 9 stable readings of each frequency, one transitional reading when the change occurred inside a certain gate time.
Actual behavior is that 80MHz portion behaves as expected, but change down to 800kHz takes several gate times (4 to >10) and sometimes I don't get a single reading before it goes back to 80MHz.

Trying smaller changes (80MHz to 79MHz, or 80MHz to 8MHz) seems to behave better. Other 100:1 pairs (10MHz down to 100kHz) also show the problem. $50 counters work as expected.

Question: Is there a setting to make the counter behave, well, as a counter - give me a frequency reading for EVERY gate period? Spec sheet says up to 200 readings per second, GPIB.


lhornburg - Re: Long time to complete measurement after frequency change
After (approximately) duplicating the set up, we were able to observer similar behavior. What we believe is happening is, as the signal is transitioning from 80 MHz to 800 kHz, the 53132A counter’s FM Tolerance specification of 25% is exceeded within the current (1s) gate period. During a measurement, the FM tolerance range is established by the input frequency at the beginning of the measurement gate. Thus, if the frequency is 80 MHz at the start of the gate, the frequency must remain within 60 MHz to 100 MHz (i.e. + 25%) during the gate period.

During the transition (hop) from the higher frequency to the lower frequency, the combination of the FM tolerance limit and the response of instrument’s prescalers to the frequency change is altering, or causing the instrument to disregard, the programmed gate time. Why this behavior does not occur on the low to high frequency transition is not known. From a programming stand point, there are no instrument settings to compensate for this.


ze - Re: Long time to complete measurement after frequency change
Thanks for the reply. Assume the prescalers, automagic decombobulators get confused when the frequency changes: after the first gate where it occurs, doesn't the instrument have enough new information about the new frequency (by simple counting) to preset to a new expected value (similar to SCPI expected freq command) and then at the next gate it would be happy again? Why does it take sometimes 6, or even ?10 gate periods to lock into a reading?

It is a nice instrument, 12dig/s takes a lot of tricks, but if all this smarts make it easily confounded, there should be a command to 'dumb it down', to make it behave at least as good as a $50 simple direct counter.

Are the new counters also like this, or will they give a reading for every gate period, back to back?
ze

Posts: 3
Registered: 04/28/08
Re: Post disappeared - censored?
Posted: Aug 2, 2011 8:39 PM   in response to: ze in response to: ze
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Thanks for looking into this. I emailed you a copy of the promotional emails I've been getting, which might have been triggered by a phone inquiry around the same time. Perhaps unsubscribing again will do the trick.
Regarding the original question, do the the new counters (that the emails are trying to sell) also behave like the 53132, taking many gate times to get a reading when the frequency switches down 100x?

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