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Author Topic: New SDRPlay RSP1A  (Read 3199 times)
W6UV
Member

Posts: 821




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« Reply #15 on: November 16, 2017, 03:32:56 PM »

What's wrong with USB?

Bandwidth. Not a problem for most users today, but as more and more installations are remote, and/or server based, and the sampling rate increases with new DDC chips, it becomes an issue.

Then there is the limitation within the host computer. There may be problems if multiple USB devices share the same bus.

I would think USB3 could help somewhat, but I don't know what else is involved. I don't recall seeing any SDR using USB3.

100BaseT Ethernet, as used on the NetSDR+, for example, offers no more bandwidth than USB2 (less, actually). I don't know of any SDR receivers with gigabit Ethernet
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VA3VF
Member

Posts: 913




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« Reply #16 on: November 16, 2017, 03:40:52 PM »

What's wrong with USB?

Bandwidth. Not a problem for most users today, but as more and more installations are remote, and/or server based, and the sampling rate increases with new DDC chips, it becomes an issue.

Then there is the limitation within the host computer. There may be problems if multiple USB devices share the same bus.

I would think USB3 could help somewhat, but I don't know what else is involved. I don't recall seeing any SDR using USB3.

100BaseT Ethernet, as used on the NetSDR+, for example, offers no more bandwidth than USB2 (less, actually). I don't know of any SDR receivers with gigabit Ethernet

Again, I don't know. If the name NetSDR+ has any connection with how it connects (sorry about that  Smiley), ethernet may have been chosen because of it, not bandwidth concerns.

Besides USB and ethernet, ok fiber as well, what other available options are consumer friendly?
« Last Edit: November 16, 2017, 03:44:12 PM by VA3VF » Logged
W6UV
Member

Posts: 821




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« Reply #17 on: November 16, 2017, 04:21:02 PM »

Besides USB and ethernet, ok fiber as well, what other available options are consumer friendly?

Thunderbolt, but it's rare outside the Apple world, hence not very consumer friendly. USB-C 3.1 has plenty of bandwidth and can power even the most power-hungry receiver, although not a 100 watt transceiver.
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VA3VF
Member

Posts: 913




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« Reply #18 on: November 16, 2017, 04:26:01 PM »

Besides USB and ethernet, ok fiber as well, what other available options are consumer friendly?

Thunderbolt, but it's rare outside the Apple world, hence not very consumer friendly. USB-C 3.1 has plenty of bandwidth and can power even the most power-hungry receiver, although not a 100 watt transceiver.

The only thing I know about apple, is that one a day keeps the doctor away. Grin Grin

Never heard of thunderbolt. Same about  USB-C 3.1. Looks like some research is in order. Smiley
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K9AQ
Member

Posts: 92




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« Reply #19 on: November 16, 2017, 06:50:04 PM »

No one wants to talk about the processing time, or latency.  The RSP1 and RSP2 have over 500 msec of processing time, making them almost useless as real time receivers when trying to work a DX pile up.  I used an RSP1 as a panadapter with my K3.  I then attempted to us the audio output for a second receiver.  The over 500 msec of latency made this unusable.  I then switched to a sound card SDR, LP Pan, and it worked MUCH better.

I still use the my SDR Play but not for a real time receiver.  I wish that they would publish this latency time for all SDR's.  I suspect this is a problem with all USB SDR's.

K9AQ
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N2DTS
Member

Posts: 744




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« Reply #20 on: November 16, 2017, 07:27:12 PM »

Almost all the delay is in the usb interface.
Its buffered and polled in the computer and there is always a lot of delay built in.
My Anan radios are ethernet and even the old Flex firewire was low latency.
If you just use it as a standalone receiver and don't need real time, usb is fine I suppose.
The elad fdm duo had very little delay though the radio, but when you used the usb port for RX it was about half a seconds worth of delay.

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N6YFM
Member

Posts: 516




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« Reply #21 on: November 16, 2017, 09:17:46 PM »

I am not buying any more usb based radios, no matter how good.

Is there a low priced ethernet based SDR? The only one I'm aware of is the Afredi (~$250), but I don't know if it's still available, or how good it is.

Low Priced is a relative definition that requires more detail to answer, such as one's income level.
For someone making $25,000 a year, a Flex 6500 would be high priced, and out of reach.
For someone who collects fine Italian Sports Cars to park on the back lot of their 20 acre ranch,
right next to their helicopter, the Flex 6500 would be "low priced" indeed.
Oh, and don't worry, it comes with Ethernet for free.  No option charge.
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VA3VF
Member

Posts: 913




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« Reply #22 on: November 17, 2017, 03:50:10 AM »

I am not buying any more usb based radios, no matter how good.

Is there a low priced ethernet based SDR? The only one I'm aware of is the Afredi (~$250), but I don't know if it's still available, or how good it is.

Low Priced is a relative definition that requires more detail to answer, such as one's income level.
For someone making $25,000 a year, a Flex 6500 would be high priced, and out of reach.
For someone who collects fine Italian Sports Cars to park on the back lot of their 20 acre ranch,
right next to their helicopter, the Flex 6500 would be "low priced" indeed.
Oh, and don't worry, it comes with Ethernet for free.  No option charge.

Fair enough. Rephrasing my question. Are there ethernet based SDRs at less than $250?
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N2DTS
Member

Posts: 744




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« Reply #23 on: November 17, 2017, 01:26:24 PM »

Not yet.
The closest would be the Anan rigs.
RF space had the net-sdr and sdr-ip receivers, not cheap...
But I do not think ethernet interface hardware is very expensive.
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ZENKI
Member

Posts: 1439




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« Reply #24 on: November 21, 2017, 12:41:51 AM »

SDRPlay could sell 1000 more if the made  RSP1A into a EMC receiver as well.

If they supported Quasi Peak, CISPR Average and CSPR RMS Average with  say 9khz and other low frequency EMC bandwidths along with limit lines they would sell thousand of these units as per-compliance receivers.

What would even  be better if SDRPLAY produced a transceiver. They seem so professional and progressive in their technical thinking I would suggest that they could produce a transceiver with both a perfect transmitter and receiver. 

SDRPLAY could also go the next step and produce a  Direct Sampling  receiver with knobs and a front panel. There a massive  hollow in the market with no real accessible high performance receivers available with a front panel. Its an perfect opportunity for them to step into this market. Besides R&S which cost a fortune there is very little other professional high performance shortwave wave receivers  makers in the market.

Amazing that SDRplay can produce a radio with such a linear s-meter and that the 4000 dollar Icom IC7610 cant exploit this basic inherent feature of direct sampling radios. I am sure that SDRPLAY could produce a better direct sampling transceiver than Icom!



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N2DTS
Member

Posts: 744




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« Reply #25 on: November 21, 2017, 05:07:50 AM »

The Elad fdm duo is an sdr in a box with knobs.
Its limited by the knobs though.
Maybe you mean an sdr receiver in a box with a LOT of knobs...
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K1YW
Member

Posts: 3




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« Reply #26 on: November 22, 2017, 10:07:46 AM »

I am not buying any more usb based radios, no matter how good.

Is there a low priced ethernet based SDR? The only one I'm aware of is the Afredi (~$250), but I don't know if it's still available, or how good it is.

I have both the SDRPlay RSP1 and the AFEDRI. The AFEDRI has only a 12 bit ADC, however this is not an issue if you adjust your front end gain properly to set it below the threshold where AM broadcast stations can create spurs in the HF spectrum. Using a BCB filter or a pre-selector easily solves this problem.  I too would not buy another USB based SDR. 
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VA3VF
Member

Posts: 913




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« Reply #27 on: November 22, 2017, 10:43:06 AM »

I too would not buy another USB based SDR. 

I can see the point, but we are talking about very affordable SDRs here ($99). I would definitively think twice if a lot more expensive.
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N2DTS
Member

Posts: 744




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« Reply #28 on: November 22, 2017, 12:08:36 PM »

I would not buy another because I already have one (RSP2) and I have the Anan ethernet based 200b.
The delay through the 200b is about the same as the Icom 7300 and the Elad fdm duo (radio).
All three of those are very close in latency, anything usb adds about 400 milliseconds.

If you just want to tune around, the rsp2 works great for the money.
Its also a great piece of test equipment.
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K7LZR
Member

Posts: 66




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« Reply #29 on: November 23, 2017, 09:39:19 AM »

SDRPlay could sell 1000 more if the made  RSP1A into a EMC receiver as well.

If they supported Quasi Peak, CISPR Average and CSPR RMS Average with  say 9khz and other low frequency EMC bandwidths along with limit lines they would sell thousand of these units as per-compliance receivers.

What would even  be better if SDRPLAY produced a transceiver. They seem so professional and progressive in their technical thinking I would suggest that they could produce a transceiver with both a perfect transmitter and receiver.  

SDRPLAY could also go the next step and produce a  Direct Sampling  receiver with knobs and a front panel. There a massive  hollow in the market with no real accessible high performance receivers available with a front panel. Its an perfect opportunity for them to step into this market. Besides R&S which cost a fortune there is very little other professional high performance shortwave wave receivers  makers in the market.

Amazing that SDRplay can produce a radio with such a linear s-meter and that the 4000 dollar Icom IC7610 cant exploit this basic inherent feature of direct sampling radios. I am sure that SDRPLAY could produce a better direct sampling transceiver than Icom!

The RSP-1x as-is makes a fine general purpose spectrum analyzer. I've been using one that way for awhile now for IF filter measurements, return loss measurements, and signal analysis. See my experiments & results on the SDRPlay forum here:

https://www.sdrplay.com/community/viewtopic.php?f=7&t=1744&p=5283&hilit=spectrum+analyzer#p5283 (Scroll to the top)

I've been bugging the SDRPlay folks to add more test-oriented(i.e. spectrum analyzer) features to their SDRUno software or else write a dedicated program for this but I don't think that either will happen any time soon so the best program for this currently is SDRSharp v1361 or older.
« Last Edit: November 23, 2017, 09:55:23 AM by K7LZR » Logged
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