External digital signal processor for HF receiver?

[KB2GOM]

Looking for something that plugs into the audio jack, might reduce some of the noise on the way through, and spit it out into my earphones.

I am particularly interested in folks who have had hands-on experience with whatever device they are talking about.

This springs out of my experience that when my horizontal room loop was connected as a simple long wire, the noise was worse, but the signal-to-noise was better, and the signal was easier to copy. So, is there anything that could be used to digitally remove some of the noise?

 

[RFI-EMI-GUY]

The AEA/Timewave DSP-599ZX is the most versatile. I have even used it to clean up cassette recordings of Inmarsat conversations taken years ago with a small antenna, and wrong bandwidth, no compander, and high noise. Really a powerful DSP. See if you can snag a nice good used one like I did.

 

[Patch42]

I would second the Timewave DSP-599zx, though I suspect it's quite a bit more than what you're asking for. Even used it costs more than many (most?) people would be looking for spend on a radio. When you learn how to use it, though, it will allow you to clean up a lot of signals that would otherwise be impossible to copy.

When I read "horizontal room loop", I'm lead to think your money would be better spent on getting a decent antenna outside, as far away as possible from interference sources.

 

[RFI-EMI-GUY]

There is one on ebay at auction for $225 right now. I bought mine for $175 NIB back when they were going for twice that.

There are lesser model Timewave model 9 and 59+ DSP's with fixed filters. Those can be had rather cheaply. The 599zx is all the DSP I will ever need. I would avoid no-name, MFJ and Radio Shack DSP's.

 

[KB2GOM]

I would second the Timewave DSP-599zx, though I suspect it's quite a bit more than what you're asking for. Even used it costs more than many (most?) people would be looking for spend on a radio. When you learn how to use it, though, it will allow you to clean up a lot of signals that would otherwise be impossible to copy.

When I read "horizontal room loop", I'm lead to think your money would be better spent on getting a decent antenna outside, as far away as possible from interference sources.

I hear you, and I agree; it's problematic.

 

[dlwtrunked]

There is one on ebay at auction for $225 right now. I bought mine for $175 NIB back when they were going for twice that.

There are lesser model Timewave model 9 and 59+ DSP's with fixed filters. Those can be had rather cheaply. The 599zx is all the DSP I will ever need. I would avoid no-name, MFJ and Radio Shack DSP's.

Agree the DSP-599zx is good, but if you can find a used JPS NR-10 (do not confuse with unrelated Yerasov product)or NR-12, do not let it get out of your sight as everything else was inferior. But Raytheon thought JPS was good also and bought them decades ago ending the product Raytheon closed JPS down in 2016 as they were primarily then external external noise voter product producers and those were becoming embedded in equipment. But sometimes a used JSP NR-10 or NR-12 shows up. They work like magic particularly on coice audio.

 

[popnokick]

Among DSP audio processors, how do these stack up to what's been mentioned thus far?
- Heil PRAS-EQ
- West Mountain Radio CLRdsp
- bhi ParaPro EQ20
- SOTAbeams WOLF100
- MFJ 616 & 618
.... gosh, a lot to choose from.

 

[KB2GOM]

Among DSP audio processors, how do these stack up to what's been mentioned thus far?
- Heil PRAS-EQ
- West Mountain Radio CLRdsp
- bhi ParaPro EQ20
- SOTAbeams WOLF100
- MFJ 616 & 618
.... gosh, a lot to choose from.

Good question. I didn't know there were so many. Has anybody ever done a bake-off between them?

 

[RFI-EMI-GUY]

Agree the DSP-599zx is good, but if you can find a used JPS NR-10 (do not confuse with unrelated Yerasov product)or NR-12, do not let it get out of your sight as everything else was inferior. But Raytheon thought JPS was good also and bought them decades ago ending the product Raytheon closed JPS down in 2016 as they were primarily then external external noise voter product producers and those were becoming embedded in equipment. But sometimes a used JSP NR-10 or NR-12 shows up. They work like magic particularly on coice audio.

I have one of those JPS SNV-4 signal to noise voters. An early version and rare beast. Tried to get a copy of the exact service manual from developer Doug Hall at JPS (not same Doug Hall of the eponymous Doug Hall Voter !) but no luck.

 

[RFI-EMI-GUY]

Among DSP audio processors, how do these stack up to what's been mentioned thus far?
- Heil PRAS-EQ
- West Mountain Radio CLRdsp
- bhi ParaPro EQ20
- SOTAbeams WOLF100
- MFJ 616 & 618
.... gosh, a lot to choose from.

Check out the reviews at eham..

https://www.eham.net/reviews/view-category?id=6

 

[krokus]

Good question. I didn't know there were so many. Has anybody ever done a bake-off between them?

I saw the GAP and the bhi at Dayton, a few years back. They both did a decent job, but have not seen them head to head.

 

[mastr]

+1 for the JPS NIR-10 it was a very good product for its time.

 

[dlwtrunked]

+1 for the JPS NIR-10 it was a very good product for its time.

In my comparisons, it still is and so is the NIR-12. Both those are probably the only equipment that I still keep from that long ago.

 

[Turbo68]

I'm using a Bhi ParaPro EQ20-DSP on my Aor 8600 MKII,Icom R71/R75 was skeptical when i bought it but once i learnet how to use it works excellent main intrest for me is only monitoring hf aircraft plus combinning it with my active loops its awesome.

Regards Lino.

 

[RFI-EMI-GUY]

It would be interesting to compare a slew of these products with same audio source. I am a bit leery about new audio products because I get the sense that audio high fidelity has become a lost art.

 

[krokus]

It would be interesting to compare a slew of these products with same audio source. I am a bit leery about new audio products because I get the sense that audio high fidelity has become a lost art.

Most of these DSP setups are for noise elimination and/or intelligibility, not fidelity.

 

[KB2GOM]

I bought one of the BHI units, here are my thoughts on it:

Jock reviews the BHI Compact In-Line Noise Eliminating Module

Many thanks to SWLing Post contributor, Jock Elliott, who shares the following guest post: The noise, the neighbor, and the box By Jock Elliott, KB2GOM Imagine the annual meeting of an internationa…

swling.com

 

[RFI-EMI-GUY]

Most of these DSP setups are for noise elimination and/or intelligibility, not fidelity.

fi·del·i·ty
(fĭ-dĕl′ĭ-tē, fī-)
n. pl. fi·del·i·ties
snip
3. The degree to which an electronic system accurately reproduces the sound or image of its input signal.

Not sure why you are trying to parse those terms.

Have you listened to a P25 radio system lately? No fidelity, terrible intelligibility. Audio levels bouncing all over the scale. I am not even confident todays engineers understand how to bias an analog circuit for minimum distortion or understand what "headroom" means in analog or digital signal processing.