Re: [Discuss-gnuradio] USRP2 dropping data

After much ado...

The VRT branch I have always returns zero for rx_missing() and rx_overruns(), with a FIXME comment. I notice this is now fixed in the latest git.

I also found no problems of lost data using Ubuntu 9.10 on an older Zotac motherboard, it wasn't until I moved to the H55-itx, and had to get the latest e1000 ethernet driver, that the missing data issue appeared. I then had the problem using the later driver on the older motherboard, which confused me. I wil try the later git code...

Checking the fractional timestamps of the received packets I found that the receive samples handler always reports the same nitems (365 in my case with a 10MHz sample rate = 3650), but the fractional count itself sometimes updates (with the new intel ethernet driver) by a multiple of this value (eg 3x), but because I'm using nitems to fwrite the data to disk, data was being skipped. I've not had a chance to check the latest git, but hopefully this is fixed.

Yes, config_mimo isn't there, I was trying to go by memory, which isn't what it used to be, or ever was...:-o

Yes UHD looks the way to go, but loks to be another learning curve and rewrite of code I've done already.

Cheers

----- Original Message ----
From: Per Zetterberg <per.zetterberg@ee.kth.se>
To: David Evans <ldeevans@yahoo.com>
Sent: Mon, 17 May, 2010 20:30:12
Subject: Re: [Discuss-gnuradio] USRP2 dropping data

David Evans wrote:
> Hi,
>
> setup...
> -2x USRP2s + GPS 10MHz reference + 1PPS
> -Single GigE port, with USRPs on GigE switch
> -Zotac H55-itx MB + i3 processor, so quite high end.
> -VRT branch code. I also use PPS via DCD line to trigger when to load time on next PPS, enable real time scheduling, ref to SMA, pps to SMA, config_mimo(MC_WE_LOCK_TO_SMA) and use similar code to rx_streaming_samples (but 2x USRPs).
> -decimation set to 10
> -feeding in same off tune carrier into RFX400s to get a sine wave, just to observe sync.
> And yet, after sampling 30 seconds of data to file from both USRPs and the code reports 0 underruns, 0 lost packets, no S's, I often get dropouts/missed packets.
> As I am receiving only, I gather from various posts that a single eth port + switch should be Ok. The data captured always starts off in sync, it just goes wrong sometime during the capture. The number of bytes captured is normally the same for both channels too.
>
> Hope you can help please,
>
>
>
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>

I have used VRT and everything has worked so far. However, I didn't do "config_mimo(MC_WE_LOCK_TO_SMA)" I did "c.ref_source=usrp2::clock_config_t::REF_SMA;" and "u2->config_clock(c);". Is "config_mimo" really part of the host VRT code ?

In any case, you and me should start to use UHD instead .....

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