Time to Switching Frequence

Andrey Sviyazov andreysviyaz at gmail.com
Fri Jun 7 11:14:48 UTC 2013


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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