Time to Switching Frequence

[Andrey Sviyazov]

Well.
It is Tx carrier frequency, which is typically below the modulated signal
on 40..60 dB.
You can see it on spectrum analyzer when there are no modulation.

Best regards,
Andrey Sviyazov.


2013/6/7 jiangwy <wyjiang at ljshuoda.com>

> **
> Hi Andrey.
>
> I see. But what's the TxLO leakage?
>
> ------------------------------
> jiangwy
>
>  *From:* Andrey Sviyazov <andreysviyaz at gmail.com>
> *Date:* 2013-06-07 19:14
> *To:* wyjiang <wyjiang at ljshuoda.com>
> *CC:* umtrx <umtrx at lists.osmocom.org>; Chemeris Alexander<alexander.chemeris at gmail.com>
> *Subject:* Re: Re: Time to Switching Frequence
>
> Hi Jiang.
>
> Sorry, I missed that you'll use only receivers.
> So, no any problems in this case.
>
> Best regards,
> Andrey Sviyazov.
> (Sent from my mobile client)
> 07.06.2013 14:54 пользователь "Andrey Sviyazov" <andreysviyaz at gmail.com>
> написал:
>
>> Hi Jiang.
>>
>> Please remember that Rx and Tx of LMS can't work well at the same
>> frequency due to PLL's problems.
>> Also, please do not forget about TxLO leakage which is quite significant.
>>
>> Best regards,
>> Andrey Sviyazov.
>> (Sent from my mobile client)
>> 07.06.2013 14:36 пользователь "jiangwy" <wyjiang at ljshuoda.com> написал:
>>
>>> **
>>> OK.
>>> Thank you and Sylvain very much!
>>>
>>> ------------------------------
>>> jiangwy
>>>
>>>  *From:* Alexander Chemeris <alexander.chemeris at gmail.com>
>>> *Date:* 2013-06-07 18:12
>>> *To:* wyjiang <wyjiang at ljshuoda.com>
>>> *CC:* UmTRX <umtrx at lists.osmocom.org>
>>> *Subject:* Re: Time to Switching Frequence
>>>  Jiang,
>>>
>>> It's not tested. LMS6002D chip by itself has quite short tuning time,
>>> but the current host and FPGA code introduce significant delay. I
>>> can't find exact numbers regarding LMS tuning time, but IIRC it was
>>> shorter than a GSM timeslot.
>>>
>>> So, as Sylvain said, given software limitations it's easier to use two
>>> channels of UmTRX to receive on two frequencies.
>>>
>>> On Fri, Jun 7, 2013 at 11:21 AM, jiangwy <wyjiang at ljshuoda.com> wrote:
>>> > Hi All,
>>> >
>>>
>>> > I have a project to monitoring ( air sniffer ) the data between GSM BTS and
>>> > MS using UmTRX.
>>>
>>> > Uplink Transmission is delayed 3 slots than downlink from specification.
>>>
>>> > So when I sync. with BTS and get the downlink slot data, I must switch the
>>> > freqs of receiver from downlink to uplink in less than 2 slots.
>>>
>>> > When the program call 'usrp_dev->set_rx_freq(wFreq)', How much time does the
>>> > UmTRX switch to the 'wFreq' ?
>>> >
>>> > Thanks in advance.
>>> >
>>> > ________________________________
>>> > Jiang WenYi
>>>
>>>
>>>
>>> --
>>> Regards,
>>> Alexander Chemeris.
>>> CEO, Fairwaves LLC / ООО УмРадио
>>> http://fairwaves.ru
>>>
>>
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