[evlatests] [Fwd: Failures to Tune, at Q-band]

[Rob Long]

I forgot to mention, I have never seen a L301 false lock problem in the 
field. If the L301 got it's command and says it is locked, it is a high 
probability that it is locked to the correct freq. Obviously this does 
not hold true for the L302 due to it's complex and high resolution 
tuning capabilities.

My suggestion is we focus on the L302s right now.

Rob

Rob Long wrote:
> If the module is in standby, it is typically not locked at all (main or 
> control or both) and thus a good indicator of failure to tune.
> 
> If the lock indicators are good, standby will NOT be set, but the 
> synthesizers could be locked to an incorrect frequency. This could be 
> due to a faulty L300 comb line, the synth/DDS did not receive it's 
> command, or a hardware problem.
> 
> The only way to know for sure would be to log the frequency command, 
> turn on the prescaler, wait for a few seconds, record the value, and 
> then turn the prescaler off again. This would allow us to determine what 
> frequency the L302 is supposed to be and if it tried to to set up or 
> false lock.
> 
> Rob
> 
> Ken Sowinski wrote:
>> Here is my summary of syntheisizer behavior
>>
>> If standby is asserted, the thing is really not working.
>> It may work again if a new frequency request is sent, or,
>> in the extreme case, it may need to be re-booted.
>>
>> If standby is not asserted it may or not be OK.  It might
>> be locked on the wrong tooth of the comn, or may not know
>> that it is not locked.
>>
>> The lock indicaotr (M_LOCK and C_LOCK) are pretty reliable
>> indicators of transient behavior when re-tuning, but not
>> reliable as an indicator of failure to lock.
>>
>> Using the standby monitor point should flag many cases of broken
>> synthesizers while not providing false positives.
>>
>>
>>
>> On Mon, 28 Nov 2011, Bryan Butler wrote:
>>
>>>
>>> i had it in my head that we never know if the L302 fails to tune.  at 
>>> least not generally.  for instance, if it locks on the wrong tooth of 
>>> the comb, we never know.  i can't say anything about the L301 - 
>>> nothing is sticking in my RAM on that one.
>>>
>>>     -bryan
>>>
>>>
>>> Rob Long wrote, On 11/28/11 16:34 PM:
>>>> Ken is right, L301s either lock or they are (hard) broken. When we see
>>>> "tuning failures", do we actually see L302 lock warnings? I can look
>>>> into archive data and get a feeling for what the synths are doing 
>>>> (but I
>>>> can not see frequency).
>>>>
>>>> Rob
>>>>
>>>> Ken Sowinski wrote:
>>>>> When this happens it is often the case that the module has given
>>>>> up and placed itself in 'standby' mode which means it will do
>>>>> nothing until it gets a new command to tune to a different frquency.
>>>>> I have no way of knowing whther this happens in every case, but I
>>>>> use it as a diagnostic when troubleshooting non-working antennas.
>>>>>
>>>>> There is a monitor point (obviously enough called 'standby')
>>>>> to reflect this state.  It could generate an alert which would cause
>>>>> flagging for the appropriate IF pair.  As a reminder:
>>>>> L302-1  ->  A0C0 or A1C1
>>>>> L302-2  ->  B0D0 or B1D1
>>>>> L302-3  ->  A2C2
>>>>> L302-4  ->  B2D2