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Re: [Discuss-gnuradio] Two channel receiver

From: Ben Hilburn
Subject: Re: [Discuss-gnuradio] Two channel receiver
Date: Tue, 7 May 2019 16:22:47 -0400

I don't personally have experience with it, but the Kerberos SDR might be worth checking out? It's effectively four coherent rtl-sdrs in a box.



On Sat, Apr 27, 2019 at 5:00 PM YENDstudio <address@hidden> wrote:
Hi Wu,

Thanks for the info. I do not have experience in FPGA programming. I am planning to use bladerf as it seems to be easier to synchronize two SDRs via the driver.

On Sat, Apr 27, 2019, 03:05 wu jo <address@hidden> wrote:
Hi YENDstudio,
if you have ability to modify the fpga code you can use 2 b210 or 2 LIMESDR to achieve that. the synchronized receive need same phase clock that is easy to get from a clock buffer from a clock source. and need the same timestamp of the sample at the same time. that need to modify the fpga to reset timestamp and output an start signal from the GPIO then another sdr receive this signal reset the timestamp. I think HACKRF use the same way to do synchronize. but HACKRF use usb 2.0 i don't know if it support LTE bandwitdh.

provide SDR, LNA, PA

发件人: Discuss-gnuradio <discuss-gnuradio-bounces+john.wu.888=address@hidden> 代表 YENDstudio <address@hidden>
发送时间: 2019年4月26日 11:54
收件人: Kyeong Su Shin
抄送: address@hidden
主题: Re: [Discuss-gnuradio] Two channel receiver
Hello Kyeong,

Thanks for the info; I will check more. It seems that some hardware modifications are required.


On Fri, Apr 26, 2019, 06:01 Kyeong Su Shin <address@hidden> wrote:
Hello YENDstudio,

I know that USRP 1 can take two RF daughterboards, but the effective sampling rate of the device in this configuration is a bit limited (probably too slow for LTE applications).

You can probably use two SDR boards with synchronization capabilities (or synchronization hacks) and a suitable clock generator. I know that my HackRF boards can do this ( https://github.com/mossmann/hackrf/wiki/Multiple-device-hardware-level-synchronization ), but I never tried this by myself (and the sample alignments can be off by ~50 samples, according to the wiki, so you have to correct that for the perfect alignment). I also know that there are a few cheap SDRs with synchronization capabilities,like AirSpy, but I never used them.

You can make your own RF frontend and add that to one of the antenna ports of a LimeSDR-like SDR by using a mixer and a clock generator (available on RF components stores, or on eBay/AliExpress, if you are willing to deal with dodgey sources). You may have to add an additional LNA (LNA4ALL? ) and/or a filter before the mixer to improve the noise figure (but you need to make sure that you are not overloading your SDR by doing so). All of these parts are available as SMA-type plug-in modules, and are in reasonable price, if you are okay with cheapo eBay/AliExpress parts.

Kyeong Su Shin

보낸 사람: YENDstudio <address@hidden>
보낸 날짜: 2019년 4월 26일 금요일 오전 1:43
받는 사람: Kyeong Su Shin
참조: address@hidden
제목: Re: [Discuss-gnuradio] Two channel receiver
I just wanted to receive time-synchronized channels. 

On Wed, Apr 24, 2019, 15:15 Kyeong Su Shin <address@hidden> wrote:
Hello YENDstudio,

Do you actually need a two-channel receiver? Maybe you can get away by using two separate SDRs (possibly synchronized with PPS and 10MHz clock) and a splitter (or two antennas). 

An another alternative would be adding a custom mixer (and a filter, if needed) between the SDR and the antenna.

Kyeong Su Shin

보낸 사람: YENDstudio <address@hidden> 대신 Discuss-gnuradio <discuss-gnuradio-bounces+ksshin=address@hidden>
보낸 날짜: 2019년 4월 24일 수요일 오후 8:03
받는 사람: address@hidden
제목: [Discuss-gnuradio] Two channel receiver

Does anyone know any affordable (not thousands) SDR which can receive two frequencies separately. I want to receive LTE UL and DL channels which can be more than 100 MHz appart. The LO offset in USRP B210 and Limesdr is not enough to cover the two frequencies with a shared frequency synthesizer.

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