I own a RSP1a and a RSPdx.  If you are interested in operation below 2 MHz the RSPdx is a big improvement over the RSP1a especially below 500 kHz. due to the additional filter and HDR mode..  The number and signal level of spurious signals  from MW stations and other high powered broadcasters in the LF/VLF region is much lower than the RSP1A.

Above 2 MHz. I think you will find that there is not much improvement with the RSPdx over the RSP1a and RSPduo because they use similar circuitry. 

One suggestion if you have trouble with local FM stations is to purchase an external FM rejection filter from NooElec on Amazon for around $10 USD.  It is much sharper at the band edges than the one in the RSP1A and does not attenuate the airband above 115 MHz. like the RSP1A built-in filter.

Another nice feature is that the RF gain control has more attenuation steps and they are smaller in size which allows you more granularity when reducing RF gain due to strong signals.

I also suggest you use SDRuno when operating in HDR mode since it had extensive software modification in order to effectively achieve a high level of performance.

Roger

Thanks for your comments. I was hoping for more response given all the buzz when the RSPdx was released, and it's compatibility and usability with SDR Console, for example, it's not clear what functions are and are not available in the latest SDRC 3.0.19 version. It does appear that the HDR mode is supported, but unclear what else. Like all other radios, these features would not be visible unless the specific radio was attached to SDRC.

As for SDRuno, while it has good intentions, I've found it to one of the least user friendly SDR programs out there, with it's poor tuning control and general ease of use lacking, which is surprising given that it's hardware is very good.

I've also looked at the Airspy HF+ for the same price, and on paper, the RSPdx offers considerably more performance, not to mention the HF+'s very limited band coverage. However, I'd entertain any discussion comparing both these radios.

Thanks,
Bill

On 1/22/2020 2:30 AM, Roger Need via Groups.Io wrote:

I own a RSP1a and a RSPdx.  If you are interested in operation below 2 MHz the RSPdx is a big improvement over the RSP1a especially below 500 kHz. due to the additional filter and HDR mode..  The number and signal level of spurious signals  from MW stations and other high powered broadcasters in the LF/VLF region is much lower than the RSP1A.

Above 2 MHz. I think you will find that there is not much improvement with the RSPdx over the RSP1a and RSPduo because they use similar circuitry. 

One suggestion if you have trouble with local FM stations is to purchase an external FM rejection filter from NooElec on Amazon for around $10 USD.  It is much sharper at the band edges than the one in the RSP1A and does not attenuate the airband above 115 MHz. like the RSP1A built-in filter.

Another nice feature is that the RF gain control has more attenuation steps and they are smaller in size which allows you more granularity when reducing RF gain due to strong signals.

I also suggest you use SDRuno when operating in HDR mode since it had extensive software modification in order to effectively achieve a high level of performance.

Roger

.

On 1/26/20 10:59 AM, Dale Elshoff WB8CJW wrote:

I used SDR Console at first but now I find SDRUno is more stable on my old I5, 8GB, 2.4GHz. laptop.  My pc is under powered for SDRC running the RSPdx even though cpu usage is lower it would often crash or lock-up often requiring a complete reboot to recover then it would run for a while and randomly lock-up, especially listening to FM broadcast or if some change were made to a menu item - gain, etc.  I would prefer to use SDRC but I need to upgrade my computer at some point before I can.

<snip>

Dale, I'm not sure I agree with your opening line.  The latest SDR Console 3.0.20 test kit (along with 3.0.19 previously for that matter) runs without crashing or lockups on my "old" 2013 HP Pavilion g6. This PC cannot be upgraded to Win10 so it's running 8.1.  It is an 1.5GHz AMD A6-3420M with Radeon HD graphics and 8Gig memory.  Along with SDR Console, I'm generally running VSPE, a VAC, CSVUserlistBrowser and Audacity at the same time. 

Not trying to start an argument, but you may have an opportunity to resolve your crashes and lock-ups before the expense of upgrading.

--
Mike

On 1/26/20 1:59 PM, Dale Elshoff WB8CJW wrote:

Hi Mike, can you provide any suggestions of how to reduce/eliminate freeze problems and improve pc performance?  I don't think stepping back to Windows 8 would be easy or necessarily productive but I'm willing to try about anything that has worked for others.  Maybe you know of a utility that would optimize the system.  I've used IO-Bit products, CCleaner, MalwareBytes from time to time.  Avast anti-virus probably knocks the performance way down but have to put up with that or something these days.

Dale,

When I decided to give Win10 a "fair shake" since I was a committed Linux user (first Ubuntu, now Linux Mint) I did a "reset" or "restore" - whatever Windows calls it.  ASUS in all their wisdom, cluttered the Win10 with all sorts of unnecessary apps.  Of course, I did a complete image first with Clonezilla so I could restore the HD to prior state. Once the image was created, Once the reset completed, I went through all the installed apps and deleted what I did not need as again Windows/ASUS apps appeared.  This made it easy for me to control Win10.  As for the HP system, I owned a Win7 DVD that I reinstalled with and allowed it to upgrade to Win8 then 8.1.  Again making sure nothing was installed that I did not want.  Both systems have been rock solid since then.  It is now to the point that I can bounce between Linux Mint and Windows on both systems with just a HD swap and the copying of 3 directories - my photos, my data files and my Thunderbird email.  My music collection it too big (350+ Gigs) to copy, so it live in parallel partitions on all the HDs.  To help keep everything in synch, Dropbox plays a big part.

I really think that the clean environment I put together for both these systems are the keys to creating a stable platform.  My third system, an i5 desktop was a homebrew with a virgin install of Windows. It's stability is what led me down the path I followed.

--
Mike

Bill

You say your main interest is HF/VLF. I would think by far the best contender here is the Airspy HF+ and Discovery. Depends as you say if you want wider band slices than 768kHz. Personally I am also mainly HF/LF and I actually wish to some extent I had got the HF+ instead of the RSP2Pro that I have here, although in truth it would be best to have both, so the RSP for wider bandwidth VHF/UHF and the HF+ of Discovery for LF/MF/HF. I don't think too much debate that the HF+ is a fine performer versus cost for HF work...... after all, that is what it was designed for. I would personally describe my RSP2Pro on HF/MF as "adequate" and not too much more, and often needs using on narrow bandwidths (I usually have it set to 500kHz) to avoid unwanted signals all over the place, but still perfectly usable for fun. I don't read too much about the newer models that says they are significantly different, as I think problem with the RSP2 is in the front-end gain distribution. I only realised recently from another post on here that on the RSP2Pro that the High-Z input has much lower front end gain then the two SMA inputs, and this makes the performance for HF far improved. Not sure if this is implemented or if lower front end gain options are available on the 1a or the DX?

There are many posts on here about "this receiver versus that receiver". I don't think some people realise that they have the very powerful feature on SDRC to easily try them all out for themselves using remote receivers. Why not try them all out for yourself using the SDRC server feature? By connecting to server-based radios you can try every radio out as if it were there with you, connected up to SDRC with all the features offered as for a local receiver. For example one of the regulars here, Kriss KA1GJU, has multiple SDR models coupled up to available servers all on excellent antennas.

If you are not familiar with this feature see Kriss's excellent step by step guide here:

https://sdr-radio.groups.io/g/main/message/53082

If you are familiar with the usual receiver "setup" then just scroll down the page a little until Kriss mentions the bit about adding receivers from the "SDRSpace" list.

There are many other stations, all with very varying antenna setups. You need to read the stations' own descriptions to see what they have.

To see info about the "other end" setup (how to get a server online so that others can listen to your receiver) see Simon's other website here, although some of the information (especially the "listening" bit, has been superseded by the above link from Kriss:
http://www.sdrspace.com/

 

Hope this helps a little in your decision.

 

73

 

Max

Thanks Max and all for your comments. I've been on the fence about the dilemma of having multiple SDR receivers and how to best to use and manage them. As it is, I'm old school in the sense that I still have my favorite Icom IC-R71A which still works great, and is hard to beat in digging out readable signals buried in the mud with its excellent Noise Blanker, P.B.T., and Notch filtering (I've yet to get the Notch filter working in SDRC). Also have an Realistic DX-300 as a backup (which I believe was made by Yeasu). My first was the battleship Collins R390A.
With the SDR's, I have been intrigued about the idea of a server, as besides being interested in HF/LF/VLF/ULF, I also have an interest in areas such as Aviation, ADS-B, Wx Sat's in the Marine/UHF bands. etc. where SDR's are uniquely suited. Thanks for the tutorial link below, something that may get me in the right direction.
As for SDR radios in general, in reading the various posts in this group, it seems that many do use multiple SDR's, but at the same time, there doesn't seem to be a Swiss Army SDR out there, and if there was, it would probably be big bucks. Like your link to setting up a server, is there any info source that describes the various SDR's and their intended uses (case studies)? For example, in the case of ADS-B, it seems that many users seem to get away with the simple RTL-SDR dongle with good results (and a good antenna).
Of course, SDR's like the ultra wideband RSP1A (which I have), along with Simon's superior SDRC, make my analog SW radios seem archaic by comparison, but in HF, the IC-R71A still gives me a nice ride.
On 1/26/2020 5:32 AM, Max wrote:

Bill

You say your main interest is HF/VLF. I would think by far the best contender here is the Airspy HF+ and Discovery. Depends as you say if you want wider band slices than 768kHz. Personally I am also mainly HF/LF and I actually wish to some extent I had got the HF+ instead of the RSP2Pro that I have here, although in truth it would be best to have both, so the RSP for wider bandwidth VHF/UHF and the HF+ of Discovery for LF/MF/HF. I don't think too much debate that the HF+ is a fine performer versus cost for HF work...... after all, that is what it was designed for. I would personally describe my RSP2Pro on HF/MF as "adequate" and not too much more, and often needs using on narrow bandwidths (I usually have it set to 500kHz) to avoid unwanted signals all over the place, but still perfectly usable for fun. I don't read too much about the newer models that says they are significantly different, as I think problem with the RSP2 is in the front-end gain distribution. I only realised recently from another post on here that on the RSP2Pro that the High-Z input has much lower front end gain then the two SMA inputs, and this makes the performance for HF far improved. Not sure if this is implemented or if lower front end gain options are available on the 1a or the DX?

There are many posts on here about "this receiver versus that receiver". I don't think some people realise that they have the very powerful feature on SDRC to easily try them all out for themselves using remote receivers. Why not try them all out for yourself using the SDRC server feature? By connecting to server-based radios you can try every radio out as if it were there with you, connected up to SDRC with all the features offered as for a local receiver. For example one of the regulars here, Kriss KA1GJU, has multiple SDR models coupled up to available servers all on excellent antennas.

If you are not familiar with this feature see Kriss's excellent step by step guide here:
https://sdr-radio.groups.io/g/main/message/53082

If you are familiar with the usual receiver "setup" then just scroll down the page a little until Kriss mentions the bit about adding receivers from the "SDRSpace" list.

There are many other stations, all with very varying antenna setups. You need to read the stations' own descriptions to see what they have.

To see info about the "other end" setup (how to get a server online so that others can listen to your receiver) see Simon's other website here, although some of the information (especially the "listening" bit, has been superseded by the above link from Kriss:
http://www.sdrspace.com/
Hope this helps a little in your decision.
73
Max

Bill

If I were in your position I would most likely consider keeping the RSP1a for VHF/UHF (inc. 6m/50MHz which the Airspy does not have) and get Airspy HF+ Discovery for LF/MF/HF if you do not mind the restriction of the 768kHz bandwidth i.e. if you do not need to monitor multiple bands at the same time. From what I read, HF+ performance is the equal or better than of any of the big manufacturer's (Yaesu/Icom etc) receivers, added to of course the superlative filtering and other features available within SDRC. Just to qualify this I should say I don;t have one but they seem pretty good when operating them remotely, as you can find out for yourself.

If you need multiple simultaneous band monitor then maybe look at something like Red Pitaya in one of its many derivatives, although this is also a transceiver, and I think you will find needs to be used with appropriate front end filter boards? Others on here will know about that better than me. Must be some users on here?

But don't take my word for it. It literally takes five minutes with SDRC and you can be testing them all out "live" and find out for yourself which ones you like operating the best.

As Joanne says, there is sadly currently not really a "one fits all" solution, or at least not at a sensible price.

Best

Max

As I said, I've been fairly happy with the RSP1A, but it's overloading sometimes can be a problem. For lack of a better description, I'm living in QRM hell (different subject), which still puts the HF+ on the table. I'd just hate to lay down $160 US just to find it's "just" better.

Bill,

With many "just better" equipment you pay a lot more for a relatively small increase in performance. Many will never notice any superiority unless different gear is carefully compared.
Personally I'm old fashioned, often want one band at a time and use a second RX if I want another at the same time.
From what I've read it seems all SDRs may be improved by external filtering. Maybe using a tight BPF could make a RSP1A more comparable to a HF+. A tight BPF would also improve the HF+ although maybe not so noticeably. LPFs would be an alternative although may not be quite so effective. Wide bandwidth is a compromise, not yet overcome by lower-priced SDRs.

73 Alan G4ZFQ

Hi Bill,

You started this thread asking about the performance of the RSPdx with respect to the RSP1A and you mentioned that you have problems with overloading from AM and VHF BC stations. Starting with the AM stations, is your problem when working the HF bands or is it specifically when you are operating in the medium wave band? If the former, did the built-in MW notch filter not help? This delivers up to 40 dB of attenuation in the MW/AM band and when combined with the 2 MHz high pass filter should allow your RSP1A to cope with really strong AM interferers. If however, your problems are really when operating in the MW/AM band, then of course that is a different matter and here you really should find a very large improvement with the RSPdx when operating in HDR mode. We are aware of users that have very strong AM transmitters in close proximity and have been able to cope with stations that deliver up to 0 dBm (1mW) at the antenna port of the RSPdx. As others have mentioned, once you get below 500 kHz, you get a double benefit in that you can access HDR mode and also the rejection of the 500 kHz low pass filter that is a 7^th order elliptic response and provides an extra 40+ dB of rejection of the AM band (on top of what the notch filter provides). In fact a MW signal that is strong enough to desensitise the RSPdx below 500 kHz is as likely to damage the receiver.

 

Please also bear in mind that none of the RSPs have built in RF AGC whereas some other radios do. In other words, RSPs are very ‘manual receivers’ and this was a deliberate design choice as it gives the user maximum flexibility, but it does mean that the radio will always need to be adjusted for best performance for each band. Some people have misunderstood this and have failed to appreciate that other receivers that seem to be less prone to overload are simply being automatically adjusted. If you really are looking for a radio that does not need adjusting at all, then the RSPdx is not for you.

 

Of course HDR mode is only available below 2 MHz and so will not help you at VHF. But again, did you find that the built in VHF BC hardware notch was not effective when you were monitoring the Air Band?

 

The notch filters on the RSPdx have been improved when compared to the RSP1A, but the improvement is no more than 10 dB.

 

In general terms, as has already been mentioned, there is always a trade-off between bandwidth and the ability of receivers to handle strong unwanted interferers. More selectivity at the front end of any receiver will always enhance its ability to handle far-off interferers, but as soon as the interferer falls into the receiver pass-band, improvements will only come with better phase noise, IMD and more effective numbers of bits in the ADCs. One extra effective bit in the ADC will get you 6.02 dB of extra dynamic range and so the difference between a 14 and a 16 bit system will only be 12 dB in this regard, which is significant, but not necessarily transformative. The difference in cost though, as you have already alluded can be very substantial.

 

We also recommend checking out the various radios which can be accessed remotely on http://www.sdrspace.com/Version-3 as suggested by Max earlier in this thread – a number of RSPdx SDRs have popped up in the last week or so. You can remotely turn the notch filters on and off and HDR mode is supported.

 

If you want to contact us directly giving us examples of the signal environment that you are having to live with at VHF, we can try to replicate that in the lab and can give you comparisons between the RSP1A and the RSPdx. Similarly  for signals in the MW/AM band.

 

Best regards

 

Jon Hudson, SDRplay