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Author Topic: New SDRPlay RSP1A  (Read 3602 times)
KS4JU
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Posts: 57




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« on: November 15, 2017, 02:47:17 PM »

An improved version of the SDRPlay RSP1

http://www.hamradioscience.com/sdrplay-rsp1a-first-look/

https://youtu.be/2PtnAtgbjJk
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HAMSTUDY
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Posts: 419




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« Reply #1 on: November 15, 2017, 10:10:40 PM »

Anyone up for summarizing the differences between the RSP1A and the RSP2?
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VK3BL
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Posts: 1364


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« Reply #2 on: November 16, 2017, 02:17:24 AM »

Anyone up for summarizing the differences between the RSP1A and the RSP2?

The most important one I've noted so far is a 14bit ADC in the RSP1A compared to the 12bit ADC in the RSP2.

The RSP1A should approach if not be on par with IC-7300 level performance.
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J.D. Mitchell - VK3BL / XU7AGA - http://vk3bl.wordpress.com
VA3VF
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Posts: 942




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« Reply #3 on: November 16, 2017, 07:32:39 AM »

Anyone up for summarizing the differences between the RSP1A and the RSP2?

The most important one I've noted so far is a 14bit ADC in the RSP1A compared to the 12bit ADC in the RSP2.

The RSP1A should approach if not be on par with IC-7300 level performance.

I just ordered an RSP1A, so I'm not disparaging it, but is it really a true 14 bit ADC? I'm not up to speed on these things, but the way it's described, it sounds like some software 'magic' is being done to achieve this claim.
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VE3WGO
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Posts: 164




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« Reply #4 on: November 16, 2017, 08:06:26 AM »

The number of bits depends on the sample rate, but it seems to be a 8 bit, 2 megasamples per second ADC (A/D converter) blocks that seem to be paralleled converters inside, configurable as per their spec below.  Audio (CD player) quality or medium res compressed digital video.

Their data sheet says:

"ADC Sample Rates
2MSPS – 10.66MSPS

ADC Number of Bits
14bit 2MSPS – 6.048MSPS
12bit 6.048MSPS – 8.064MSPS
10bit 8.064MSPS – 9.216MSPS
8bit >9.216MSPS

"

And it has a DVB tuner in front of the A/D converter so it's not a direct sampling type of SDR.  For full 14 bits, you have to stay in small chunks of spectrum at a time.

Still, 14 bits does give you 84 dB of dynamic range.  Kind of average in that regard, but good for the price.

73, Ed VE3WGO
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VA3VF
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Posts: 942




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« Reply #5 on: November 16, 2017, 08:16:34 AM »

The number of bits depends on the sample rate, but it seems to be a 8 bit, 2 megasamples per second ADC (A/D converter) blocks that seem to be paralleled converters inside, configurable as per their spec below.  Audio (CD player) quality or medium res compressed digital video.

Their data sheet says:

"ADC Sample Rates
2MSPS – 10.66MSPS

ADC Number of Bits
14bit 2MSPS – 6.048MSPS
12bit 6.048MSPS – 8.064MSPS
10bit 8.064MSPS – 9.216MSPS
8bit >9.216MSPS

"

And it has a DVB tuner in front of the A/D converter so it's not a direct sampling type of SDR.  For full 14 bits, you have to stay in small chunks of spectrum at a time.

Still, 14 bits does give you 84 dB of dynamic range.  Kind of average in that regard, but good for the price.

73, Ed VE3WGO

Thank you very much for the explanation, Ed. There is some 'massaging' involved then.

Even 6 MSPS is too much for what I need. Can the number of bits be scaled even higher for 1 MSPS?  Grin Just kidding.

I completely forgot about the DVB tuner, and the fact that in this case it's not a direct sampling type SDR. Still, for the price, it should be a reasonably good value.

A think the new AirSpy HF+ also does some 'magic'. Need to start saving for that one.

I know, why not add the amounts and go for an Elad. It's all part of the fun. Roll Eyes

73 de Vince, VA3VF
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N0YXB
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Posts: 1142




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« Reply #6 on: November 16, 2017, 08:23:49 AM »

Anyone up for summarizing the differences between the RSP1A and the RSP2?

Some highlights from HRO:
   
ADC resolution increased to 14-bit native for sample rates below 6 MHz, increasing to 16 bits with decimation.
Enhanced RF pre-selection (greater filter selectivity plus 4 additional sub-bands compared to the original RSP1) for reduced levels of spurious responses.
Improved LNA architecture with variable gain. The RSP1 has just a single gain step.
Improved intermodulation performance.
Performance extended to cover 1kHz to 2 GHz with a single antenna port.
Bias-T facility.
Improved frequency stability incorporating a 0.5ppm TCXO (software trimmable to 0.01ppm).
Selectable broadcast AM/FM/DAB notch filters.
RF shielding within the robust plastic casing.
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VA3VF
Member

Posts: 942




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« Reply #7 on: November 16, 2017, 08:28:46 AM »

Some highlights from HRO:

Those are the improvements over the RSP1, I think. I have not checked line by line, but the gap between the RSP1A and the RSP2 is very narrow now. Main differences are antenna ports and the metal case option.
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VA3VF
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Posts: 942




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« Reply #8 on: November 16, 2017, 10:17:04 AM »

Even 6 MSPS is too much for what I need. Can the number of bits be scaled even higher for 1 MSPS?  Grin Just kidding.

My joke may not have been totally of the wall. From the RTL-SDR Blog review of the RSP1A:

"ADC Resolution Increased to 14-bits: The RSP1A uses the same ADC chip as the RSP1, but now has unlocked 14-bit ADC capability for bandwidths below 6 MHz thanks to onboard decimation and oversampling. So now 14-bit data comes directly into the PC if using a bandwidth below 6 MHz. Further decimation can still be achieved within software like SDRuno."

SDRPlay also has a technical reply explaining how it's done. Check the RTL-SDR Blog.

https://www.rtl-sdr.com/a-review-of-the-sdrplay-rsp1a/
« Last Edit: November 16, 2017, 10:19:24 AM by VA3VF » Logged
N6YFM
Member

Posts: 517




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« Reply #9 on: November 16, 2017, 11:17:35 AM »

Hah.   SDRplay needs to step up their game.

The AirSpy HF+ model for $199 has specs that mop the floor with this....
https://www.rtl-sdr.com/tag/airspy-hf/

In summary, a MDS of -140dbm.
HF coverage between 9 kHz .. 31 MHz
VHF coverage between 60 .. 260 MHz
-140.0 dBm (0.02 µV / 50 ohms at 15MHz) MDS Typ. at 500Hz bandwidth in HF
-141.5 dBm MDS Typ. at 500 Hz bandwidth in FM Broadcast Band (60 – 108 MHz)
-142.5 dBm MDS Typ. at 500 Hz bandwidth in VHF Aviation Band (118 – 136 MHz)
-140.5 dBm MDS Typ. at 500 Hz bandwidth in VHF Commercial Band (136 – 174 MHz)
-140.0 dBm MDS Typ. at 500 Hz bandwidth in the upper VHF Band (> 174 MHz)
+15 dBm IIP3 on HF at maximum gain
+13 dBm IIP3 on VHF at maximum gain
110 dB blocking dynamic range (BDR) in HF
95 dB blocking dynamic range (BDR) in VHF
150+ dB combined selectivity (hardware + software)
120 dB Image Rejection (software)
Up to 660 kHz alias and image free output for 768 ksps IQ
18 bit Embedded Digital Down Converter (DDC)
22 bit! Resolution at 3 kHz channel using State of the Art DDC (SDR# and SDR-Console)
+10 dBm Maximum RF input
0.5 ppm high precision, low phase noise clock
1 PPB! frequency adjustment capability
Very low phase noise PLL (-110 dBc/Hz @ 1kHz separation @ 100 MHz)
Best Noise reduction of the market using state of the art algorithms
2 x High Dynamic Range Sigma Delta ADCs @ up to 36 MSPS
No Silicon RF switch to introduce IMD in the HF path
Routable RF inputs with simple modification
Wide Band RF filter bank
Tracking RF filters
Sharp IF filters with 0.1 dB ripple
Smart AGC with real time optimization of the gain distribution
All RF inputs are matched to 50 ohms
4 x Programmable GPIO’s
No drivers required! 100% Plug-and-play on Windows Vista, Seven, 8, 8.1 and 10
Industrial Operating Temperature: -45°C to 85°C
Full details at https://airspy.com/airspy-hf-plus/

Block diagram and more details here;
https://www.itead.cc/airspy-hf-plus.html
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VA3VF
Member

Posts: 942




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« Reply #10 on: November 16, 2017, 11:22:47 AM »

Hah.   SDRplay needs to step up their game.

The AirSpy HF+ model for $199 has specs that mop the floor with this....

Up to 660 kHz alias and image free output for 768 ksps IQ


Certainly, no doubt about it, but the 660 kHz is a limitation to a lot of people. It does not affect me, and I plan to purchase an HF+ as well.

The price difference is not that great, personal finances aside, even though it's a 100% premium.  Grin Grin Grin Grin

The problem with these types of discussions, is that it inevitably turns into 'religion', in the bad sense of the word.

Aren't we lucky to have some variety at different price points?
« Last Edit: November 16, 2017, 11:30:51 AM by VA3VF » Logged
N2DTS
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Posts: 748




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« Reply #11 on: November 16, 2017, 01:21:14 PM »

I am not buying any more usb based radios, no matter how good.
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VA3VF
Member

Posts: 942




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« Reply #12 on: November 16, 2017, 02:24:44 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.
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W6UV
Member

Posts: 828




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« Reply #13 on: November 16, 2017, 03:13:44 PM »

What's wrong with USB?
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VA3VF
Member

Posts: 942




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« Reply #14 on: November 16, 2017, 03:17:33 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.
« Last Edit: November 16, 2017, 03:24:09 PM by VA3VF » Logged
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