LimeSDR-Mini Problems with DATV-Express

The place to discuss the use of the LimeSDR Mini for amateur TV applications
G8GKQ
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Re: LimeSDR-Mini Problems with DATV-Express

Post by G8GKQ » Sun Feb 03, 2019 10:49 am

Hi Shaun

That's not what I meant. I believe that the LimeSDR Mini does perform well with good USB3 hardware and drivers, it's just that poor computer USB3 implementations (hardware and drivers) have been a source of trouble for a number of LimeSDR users.

Of course the Portsdown is limited to the USB2 on the Raspberry Pi.

Dave

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Re: LimeSDR-Mini Problems with DATV-Express

Post by G4GUO » Sun Feb 03, 2019 10:51 am

No the Lime uses USB3.

As far as settings are concerned I just use default settings.

In the LimeSuite one option that can be set is to trade latency vs performance
my code chooses maximum performance (highest latency), that is not a user settable value though.

I also only use motherboards with Intel chipsets.

- Charles

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Re: LimeSDR-Mini Problems with DATV-Express

Post by G4GUO » Sun Feb 03, 2019 11:04 am

As far as USB2 is concerned.

The DATV-Express hardware is capable of 10 MS/s with no dropouts but I have hand crafted
the FPGA code for high speed transfer between the USB2 controller chip and the FPGA. I feed
a very large FIFO inside the FPGA.

Even with all that it seems I am one of the few people able to achieve those sustained transfer rates
so I can only conclude it is a PC hardware problem. How fast the processor is does not seem to matter
(within reason of course).

- Charles

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Re: LimeSDR-Mini Problems with DATV-Express

Post by VK5YYY » Sun Feb 03, 2019 12:53 pm

Hi Charles,

Could you please share with us your PC brand/era/build spec?
and maybe your best guess minimum spec to get higher msym
Is there anything else except Intel chipset that you feel might be key

Cheers Roger VK5YYY

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Re: LimeSDR-Mini Problems with DATV-Express

Post by G4GUO » Sun Feb 03, 2019 4:11 pm

Hello Roger,

Mostly I build my own P.Cs so anything I have is no longer available.
You can't go too wrong with an Intel chipset.
This post from the Ettus Research forum seems to agree with me
http://lists.ettus.com/pipermail/usrp-u ... 16271.html

That post is out of date as I think all my current PCs use USB 3.1 rather than 3.0

- Charles

g4ouk
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Re: LimeSDR-Mini Problems with DATV-Express

Post by g4ouk » Sun Feb 10, 2019 12:48 pm

G4GUO wrote:
Sun Feb 03, 2019 9:09 am
You will be waiting a long time as it is not a DATV-Express issue.
DATV-Express uses LimeSuite which is an interface library provided by Lime themselves.
My P.C is capable of well in excess of 4MS/s with a Mini.

- Charles
Yes I will be waiting a long time for this to get fixed because everyone seems more interested in Low Symbol Rates with the Portsdown on Bands not meant for Wide Band Modes such as 50, 70 and 144 Mhz. Your P.C may be capable of well in excess of 4 MS/s but many are not as lucky as you as seen in other posts. I can also use 4MS/s without difficulty using my existing Pluto which only has USB2 even though it is plugged into the same USB3 Ports and yes both PC's I have are Intel Chipsets with USB 3.1 implementation

As Dave say's you and him have better things to do than implement the latest Lime Suite Firmware Version to work with DATV-Express when the Portsdown work perfectly, but not all of us are using the Portsdown.

I wish I had not bought the Lime Mini now but thanks anyway.

SImon

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Re: LimeSDR-Mini Problems with DATV-Express

Post by g4ouk » Sun Feb 10, 2019 1:24 pm

g0mjw wrote:
Sun Feb 03, 2019 9:53 am
g4ouk wrote:
Sat Feb 02, 2019 9:12 pm
Hi Dave,

Thanks for confirming I have the latest version of Firmware 5 and Gateware 1.27. I'm trying to use 4ms/s H262 MPEG2 for our local repeater so maybe its a software driver issue with the Lime not being able to handle that amount of data through the USB3, very odd. So really until a software upgrade on DATV Express happens which can benefit from taking advantage of USB3 I probably won't be able to use my Lime with our repeater. I will test out using 2ms/s in the shack just to confirm that 2ms/s works okay, it should be fine on an i7 with DATV Express.

Thanks again for your help

Simon, G4OUK
Perhaps instead you should be thinking about reducing the bandwidth of the repeater and moving to H264? That would have several benefits, including increased sensitivity.

Mike
Hi Mike,

There is a reason we still use H262 MPEG2 on our local repeater at 4MS/s, availability of cheap receivers and more straight forward transmitters plus we should be utilizing all the bandwidth we are allocated for this use. The UHF and Microwave Bands are under threat and we should be utilising them fully, if we don't we are giving a green light to Ofcom to sell them off and we'll all suffer. We have already lost part of 2.4Ghz and 10 Ghz and 3Ghz will most likely be next if 5G is confirmed. Yes H264 is a great mode and has potential S/N benefits to us so why are we bothering with 2 MS/s when we could utilize 4 MS/s H264 at Full HD, most people have an HD camcorder round the house and they are cheap nowadays, just a thought !

Sorry bit off topic.

Simon

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Re: LimeSDR-Mini Problems with DATV-Express

Post by G4GUO » Sun Feb 10, 2019 1:58 pm

Simon, there is nothing I can do about it, the problem is in a part of the system that I have no control over.

- Charles

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Re: LimeSDR-Mini Problems with DATV-Express

Post by G8DKC » Sun Feb 10, 2019 2:41 pm

Hi Simon,

Have a look at my comments on...

viewtopic.php?f=82&t=5839&p=18068&hilit=h264#p18067

It's so easy to loop through another sat rx on 23 or 70, etc.

I've just ordered a HDMI switch to mod to work on lock light, as an experiment, just in-case needed.

Ivor and Shaun have done lots on GB3ZZ.

I say add not take away, put in extra receivers, then all are happy, well if only we could be :)

G8GKQ
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Re: LimeSDR-Mini Problems with DATV-Express

Post by G8GKQ » Sun Feb 10, 2019 4:55 pm

In one of the posts above, I made this comment:
G8GKQ wrote:
Sat Feb 02, 2019 2:20 pm
Note that the latest gateware version available online is 1.28, but this may not be compatible with Portsdown or DATV Express. Charles and I have better things to do than go chasing new versions when the old one works perfectly!
It has been pointed out to me that this might be taken the wrong way. Some explanation:

The team at Lime Microsystems are (like the Portsdown and DATV Express teams) continually trying to improve their software. To achieve this, they issue a new version of gateware and firmware for LimeSDR Mini and LimeSDR USB each month. What I was trying to say is that Charles and I will not update the Portsdown and DATV Express software every month to track these changes. Every 3-6 months is more reasonable.

To manage this, the "Lime Config" menu in the Portsdown software (latest version) has a button "Update Lime FW". This button will update your LimeSDR to the gateware/firmware standard required for the current Portsdown software. If you have updated the gateware/firmware beyond the required version, the button "Force Lime FW" will downgrade you as required.

So, all I was trying to say is that we will not be reacting to every single update published by Lime Microsytems but will update when required to improve the Portsdown capability with Lime.

Or "don't worry, it will continue to work and we will upgrade it when we can".

Dave, G8GKQ

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