Low symbol rate receivers

The place to discuss reduced bandwidth fast scan amateur television on 70cms and below
g8gtz
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Joined: Wed Apr 07, 2010 6:26 pm

Low symbol rate receivers

Post by g8gtz » Tue Dec 02, 2014 10:46 pm

Most brands, including technomate, seem to spec down to 800 Ksymbols so I presume that is the spec of the chipsets they all use...

However, G1XFG just pointed me to http://www.dr-hd.com/product/receivers.html - the F15 looks interesting and they say in the FAQ page:

"Q. Can we receive extremely low-SR SCPC channels?

A. Yes! Our receivers are already recognized in the DX communities around the world because of that, and because of other functions, too.
All our receivers are tested and according to our official specification, they can work with any SR from 1000-45000. (As you see, we have wider SR rate than most boxes in the market.) However, our models are exceeding the published specifications. For example, using the Dr.HD F16 model, there were reports of stable reception of channels with SR=300, 250 and even below! About the new D15/Grand receivers - the actual lowest SR shall be confirmed by our customers (we can not test it in out labs, as real reception from some special satellites is needed), we will be happy to receive confirmations/contributions and publish them here."

They are about £100 and Satcure the UK stockist is out of stock http://satsecure.uk/tv-home-cinema/set- ... s.html?p=2 so they only seem to be available from a store in Germany http://drhd.tictail.com/

Has anyone had experience with them?

73
Noel - G8GTZ

G8DPH
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Joined: Fri Mar 01, 2013 4:44 pm

Re: Low symbol rate receivers

Post by G8DPH » Tue Dec 02, 2014 11:22 pm

The D15 seems to be in stock here:
http://www.sateuropa.co.uk/cart/catalog ... 01153.html

G8DPH
Ashley
G8DPH

G8DPH
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Joined: Fri Mar 01, 2013 4:44 pm

Re: Low symbol rate receivers

Post by G8DPH » Wed Dec 03, 2014 11:34 am

The F16 and F15 are old models - replaced by the D15.

See http://www.dr-hd.com/product/receivers/drhd-d15.html

G8DPH
Ashley
G8DPH

g8gtz
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Joined: Wed Apr 07, 2010 6:26 pm

Re: Low symbol rate receivers

Post by g8gtz » Thu Dec 04, 2014 11:06 am

F6DZP has commented that receiving Reduced bandwidth DATV (RB-TV) is more difficult than transmitting it and no STB can be guaranteed to work below 1Ms/s as the DVB-S2 chipsets are not designed to go below that rate.

Also this review http://radiovibrations.com/testreports/dr-hd-d15.htm of the D15 says:

"The lowest symbol rate i got was 1090. 8PSK detection is possible but requires stronger signals."

Noel - G8GTZ

G4GUO
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Re: Low symbol rate receivers

Post by G4GUO » Thu Dec 04, 2014 11:20 am

The expression "square pegs in round holes" comes to mind.

- C

g8gtz
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Joined: Wed Apr 07, 2010 6:26 pm

Re: Low symbol rate receivers

Post by g8gtz » Thu Mar 05, 2015 7:20 pm

Brian,
Ian and I have been mulling over the problem of a lack of suitable receivers for very low symbol rate transmissions, which is going to be a barrier to entry for many. I have searched around and looked at what the satellite feed hunters are using. I came across the TBS5925 from http://www.tbsdtv.com . This is a USB connected satellite TV tuner card which the manufacturers specify down to 200ks/s on DVB-S & DVB-S2. There is also a PCI version TBS6925. I wonder has anyone tried one and do the experts think it might be suitable to our use?
Shaun.
So the answer is probably not - however, as Brian said there are a couple of people looking at using a Sharp tuner module (plenty available) which uses the same chipset as the S2-1600 and a small OBC to drive it and do the decode - if anyone can help with writing code for the RPi I'm sure they would appreciate some help.

Watch this space or CQ-TV.

73

Noel

g8vpg
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Joined: Fri Oct 11, 2013 9:35 am

Re: Low symbol rate receivers

Post by g8vpg » Thu Mar 05, 2015 7:40 pm

Noel,
I am puzzled why you think the TBS5925 is not suitable for NB-DATV. Unlike the set top boxes mentioned above, which are specified to 1000ks/s but may go lower, this device is actually designed to go down to 200ks/s.
Shaun.

g8vpg
Posts: 310
Joined: Fri Oct 11, 2013 9:35 am

Re: Low symbol rate receivers

Post by g8vpg » Thu Mar 05, 2015 7:51 pm

Just found a review of the TBS5925 which seems to confirm the low SR capability, radiovibrations.com, satellite DX page.
Shaun.

g8gtz
Posts: 1154
Joined: Wed Apr 07, 2010 6:26 pm

Re: Low symbol rate receivers

Post by g8gtz » Fri Mar 06, 2015 8:55 am

Hi Shaun,

I came to that conclusion based purely on the comment from F6DZP, who knows far more about this topic than I do, when I asked a similar question to yours about the F15 STB:
F6DZP has commented that receiving Reduced bandwidth DATV (RB-TV) is more difficult than transmitting it and no STB can be guaranteed to work below 1Ms/s as the DVB-S2 chipsets are not designed to go below that rate.
Judging by the spec http://www.tbsdtv.com/products/tbs5925- ... r-usb.html it looks a very interesting USB device that would do what we need - but at a price (it's a "professional unit") and it still needs a PC...

73

Noel - G8GTZ

F6DZP
Posts: 203
Joined: Fri May 27, 2011 9:59 am

Re: Low symbol rate receivers

Post by F6DZP » Thu Mar 12, 2015 4:16 pm

Tutioune1600 has reached now a good setup for NB DATV (and standard DATV) :)
I have finished yesterday the manual (84 pages). ;)
TT S2-1600 is no more on the market. :oops:


:idea: I plan to Develop now Tutioune for TBS 5980 (or Prof 7500?) that has same chips as S2-1600, so same possibilities
and it is a USB tuner, laptop could be used.
Price can be acceptable.

Jean Pierre F6DZP

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