Noise Levels and FT8 - My new 6600 seems to have poor hearing

Kevin Rich

I just received my 6600 yesterday and getting it up and on the air was super easy. I watched a few videos from Mike and have SmartSDR installed and DAX and CAT configured to work with  WSJT-X. Having everything built in to the rig and software that works out of the box is great and this was the easiest setup I have done for digital operations. 

A little more background. I have been operating digital modes for a couple of years and with various rigs including a FTdx-3000, FT-991, IC-9100, and Elecraft K3S. I also have an SDRPlay RSP2 and HDSDR running. Out of all the rigs I use, sadly the SDRPlay RSP2 w/HDSDR performs better than the rest for decoding signals and "hearing" things I just can't hear on the other rigs. Because of that, I recently sold the K3S and bought the 6600 assuming that it should perform at least as well as the SDRPlay and probably much better but so far that is not the case and I can only assume I do not have things setup correctly because the SDRPlay is decoding WAY more signals than the new 6600. The 6600 does decode and I have made QSOs but in every interval the SDRPlay decodes 3x to 5x more signals and in the examples where they both decode the same signal the 6600 is 10 -  15 dB weaker (i.e +2 vs -14).

I have the 6600 directly connected to Ethernet and am running SSDR, DAX, and CAT on a WIndows 10 laptop on the same network with everything operating correctly. Network bandwidth and latency don't seem to be an issue. I have attempted to adjust AGC-T like I have seen in several videos all with no substantial results. I have played with the WNB and NB controls and levels. I have tried in DIGU and also USB using some NR. I followed the guidance in a post from Gerald to check the noise with an unconnected antenna and then connected and reduced the Preamp to -8 to achieve as close as I can to 8dB - 10dB  of difference and even at -8 on the preamp I still have about 15dB difference. Antenna is a 20m resonant dipole in the attic (HOA restrictions) 

I am hopeful that I am somehow missing the obvious and someone can share a tip with me on how to reduce the noise or pull in weak signals or whatever else needs to be done. 

I am still in the stage where I refuse to believe that a $150 SDR with free software consistently out performs a $4000 radio with commercially developed software. 

Thanks in advance,

-Kevin

Michael N3LI

Hi Kevin.  Lack of hearing is an odd problem for a 6600. I definitely don't have that issue on mine, I can hear better than a lot of the people I am contacting, if wsprnet and PSKreporter are showing.

I've been on maestro this morning. If you like, I'll switch to SSDR and we can compare settings.

Kevin Rich

Michael, thanks for the offer. I am on a work related call until about 11:30 Mountain and then have some time if you are still available.
 

KJ7G

Hi Kevin,
During my first month I was about to return my 6600M because of the exactly same issue. Flex have a couple videos and posts regarding adjustment of AGC-T and preamp but it does not help for FT8. The loss of dynamic range when multiple signals present within passband filter is well known disadvantage of SDRs and I surprised with your report of SDRplay performance. For comparison I used splitter to connect the same antenna to 6600M and K3S and run 2 instances of WSJT-X side by side showing about 20% less decodes from 6600M using recommended settings. I used this setup to identify optimal settings below and was able to achieve almost identical performance.
I decided to keep 6600 just because of convenience and remote features and found that following settings significantly improve FT8 reception for me:
- Turn AGC-T OFF
- Set gain slider between 10 and 20, not higher. I often keep it at 10 when band is busy
- Keep Rx gain in DAX at default 50
- Adjust preamp setting to have WSJT-X bar showing 30-40 dB
Hope it helps,
73
Boris KJ7G

Kevin Rich

Thanks Boris. I use a similar setup to compare the two radios. I am sharing the same antenna with the MFJ-1708SDR and I just tried those settings and don't see much change. I am decoding at least 50% less and usually 75% less or higher than the SDRPlay.  I have tried the AGC at off, slow, med, and fast and adjusted the level in all modes and used -8, 0, +8, +16, +24 on the preamp all while keeping the levels in WSJT-X between 30dB and 40dB which is the same as I run wiht the other rigs.

I am aware that the MFJ-1708 is not the greatest product on the market but even when I remove it form the path I get the same results and no better decodes. 

Michael N3LI

Roger that. Let me post some of my settinga as a start. Some are certainly what you are doing now, but can't hurt being thorough.

SSDR settings:

I'll set 20 meters

Ant: 1 RF gain 8
WNB off
Display
avg 50
fps 25
Weighted avg off
gain 30
Black Auto
Rate 80
No DAX IQ
AGC Med
No DSP
Digu 3K
No RIT or XIT
Dax Channel 1

Dax Control Panel

Streaming TX at 39
Slice A Streaming at 50

SmartSDR Cat Control panel
Serial Com6 Process WSJT-X
TCP Port 5002 Slice A

Power - varies
P/CW Window Dax on
Proc off

WSJT
Settings

Kenwood TS-2000
Serial Com 6
9600 Baud
8 Data Bits
1 Stop Bit
Handshake None

PTT method CAT

Mode None

Split operation None

Audio
Input DAX Audio RX 1
Output Dax Audio TX

Advanced

Random Erasure Patterns 6
Two Pass decoding checked

Receiver Bandwidth 2.5 KHz

Main screen

Power set at 100 percent
Receiving at 60 DB

20 meters is pretty crowded at the moment. Anyhow, check to see if this helps.

Mike-VA3MW

I can't comment on the SDRPlay, even though I own one and wasn't seriously impressed with any of the software it comes with.

However, this morning I was copying 6M FT8 signals on my 6600 down to -24db and while I don't have different model receiver to compare with, my settings are full gain (my noise floor is -140db when looked at on the waterfall), AGC-T set as required.  

The same is true for 160M, but the preamps are off and I can hear very very well.  In fact, it is pretty annoying when you call a guy in Turkey on 160M and he can't copy you to answer you.

Make sure that WSTJ is setup correctly and has the right number of Bins/Pixel.  If you only see from 0-1200hz in the WSJT waterfall, those are the only signals you are going to copy.  This is a common problem for not copying all the signals.  

The SDR technology in the Flex is radically different than that of the SDRPlay and not subject to the same overload issues.  Not all SDR technology is created equal.  In fact, and this is a very key point our Dynamic Range increases with more signals in the pass band.  

If you want to dig under the covers on SDR overload, this is a great article.  https://community.flexradio.com/flexradio/topics/adc-overload-myths-debunked.  Our CTO Steve Hicks authored it.

Mike

Kevin Rich

Michael, 

Thanks for sharing your settings, mine were already nearly identical with the exception that I have WSJT-X radio configured for FlexRadio 6xxx using the network server for CAT control and RTS/COM5 for PTT.

In the latest decode interval I have 20 decodes on the SDRPlay RSP2 and 4 on the 6600.

-Kevin

Mike-VA3MW

Something is not right.  Can you stop and restart DAX?  Is your radio on a Local LAN or is any part WiFi?  

There is something contributing to your bad audio on the DAX channel or RF signal making it to the radio.

Can you swap the feedlines from the SDRPlay and the Radio?  

Screen shots of the SmartSDR screen would be very helpful.

KJ7G

Hi Mike,
Thanks for great article but it focused for the SSB/CW case when multiple signals are present on the band but only one within selected filter. Could someone at Flex actually perform side by side FT8 tests with superhet when you have 30-40 signalls within 3k filter?
I found old video on my phone showing difference, 6600 is on left side and K3S makes much more decodes on the right:

https://www.icloud.com/attachment/?u=https%3A%2F%2Fcvws.icloud-content.com%2FB%2FAc3b59SMZu8cRlxBgvHOIVR5n0jxAX5enIwXzO2vMwqz8KZlMSAcSv7I%2F%24%7Bf%7D%3Fo%3DAqclvuJ2HLVwdqY15UYQdAZh2pSPaj28zNT1yR3dui4S%26v%3D1%26x%3D3%26a%3DCAog5J8GlQXqZmPhyaxKzHFVjTsOejuJDHtLaipF9wrpn9QSGxCltrTntC0Ypcavu74tIgEAKggByAD_SSJadg%26e%3D1562955735%26k%3D%24%7Buk%7D%26fl%3D%26r%3D90F826E8-89BE-41BF-AF5E-50467B72C3B7-1%26ckc%3Dcom.apple.largeattachment%26ckz%3D4523A8DA-ADA9-40D6-AA82-731E72E4744A%26p%3D56%26s%3DYhxAD4TgmivhxunN80wrDeEB8Iw&uk=ChrYZNEF1qmFeaeco3uo4w&f=IMG_0459.MOV&sz=146072806

Boris

Michael N3LI

Michael - I've had the same problem with me hearing them better than they hear me. I can see my signal's hitting the area. 

Ohh, the trials and tribulations of owning a great radio.... 8^)

WX7Y

The only Noise limiting DSP filters that really doesn't effect MY digital RX Signals is the "WNB"  which I run ALL the time here, DO NOT RUN "NB",  "ANF" or "NR" I exclusively use just the AGC-T, at my QTH I run it at 37 on 40 Meters.
73's
Bret
WX7Y

Mike-VA3MW

This is 20m for me right now on a HF6V at 44 degrees north (north of Toronto).

The Radio is a 6600.

Larry Loen WO7R

I have not found the default settings on SmartSDR to be the best.

Usually, they set audio volume in the middle and the AGC too high.  I usually turn _up_ the audio and turn the AGC down to somewhere between +28 to +40.  I typically run AGC at "medium" even though many suggests best practices would be to turn it off altogether on FT8.  I certainly turn off the speech processing when Transmitting on FT8.

From Central Arizona, I am hearing France on 6m (worked one of two) and even decoded Turkey (3 times, 7000 miles) just today.  You might want to go into the "ANT" display and experiment with how much preamplification you need for best results.  You may have to turn it down, especially on the low bands.

Meanwhile,  I think it is safe to say my 6400 hears well.

Kevin Rich

Mike - Thanks for the reply. I have swapped them and also have had the antenna feedline directly connected to the 6600. I have stopped and started several times. The 6600 is receiving and decoding and I have made QSOs. It just doesn't decode as many signals and the ones it does decode are much weaker. 

I have operated the 6600 with Ethernet connected to the local LAN and SSDR connecting to the rig from a laptop running wireless. I have also connected the laptop and 6600 with just an Ethernet cable between and eliminating any LAN issues. The is now discernible difference when connected either way. I have also tried operating from two separate PCs. Both of the systems are the same hardware and OS (Windows 10) as the laptop I use with other rigs and the SDRPlay. If I turn the NR *off* on the SDRPlay I get similar results from my noisy QTH. 

I'll snap a couple of pics of the SSDR and post them shortly.   

Kevin Rich

Mike - here a couple of pics of the setup showing them both. Taken within a few minutes of each other. It doesn't seem to matter where I adjust the preamp on the 6600. The results are about the same. I changed it to +8 in this image to match what you had. I just seem to have a huge amount of noise at this QTH. 

Being new to Flex and SSDR I am sure I am probably missing some simple setting. Happy to send other pictures or describe other settings if it will be helpful to the folks reading this.

Mike-VA3MW

I have converted this to a support ticket.

Kevin Rich

Thanks Mike. Apologies is this was the wrong area to post this in.

-Kevin

KJ7G

I don't think anyone denying that Flex is the great radio. I have the same positive experience with 6600M hearing better than many remote stations and I also observe many stations using wrong filters, especially with Icom radios. I have no issues with 6600M receiving weak signals from every DXpedition, Turkey, Kuwait, India, Mongolia, anywhere.
But it is not relevant for reported FT8 issue how good is receiver or antenna, location or propagation. 
if you will check my video then 6600 frequently have better SNR report than superhet on the same antenna connected to both radios using simple T connector.
It seems like when strong signal is present WSJT-X missing decodes with 6600 and missed signals are not necessary weakest. 
For regular user having single radio Flex appears working perfectly great with FT8. To recognize issue you need to compare different radios side by side like I did or how Kevin is doing now. It seems like there is an improvement opportunity for Flex team if someone will try investigating complaint form more than 1 customer.

Larry Benoit

Hi Kevin,

While unlikely, you may have a corrupt or misconfigured DAX channel. I suggest you try configuring the WSJT-X input to DAX Audio RX 2 or RX 3, if you have not already done so. 

Additionally, you may want to confirm Windows Sound settings for the DAX channels.  Open Windows Sound > Playback, find DAX RESERVED AUDIO RX 1 (and 2 through 8) > Properties > Advanced  and confirm they are set to 2 Channel, 16 bit, 48000 Hz (DVD Quality).  Also, check mark both Exclusive Mode boxes. If there are any settings for audio enhancements, sound effects, spatial sound,etc., disable all of them.  

Good luck and 73,
Larry KB1VFU

David Decoons, wo2x

Kevin Looks like you do indeed have a lot of noise (noise floor around -108). I get hit with power line noise here which has similar signature on panadapter. I run the WNB on when that happens and run the level at 93. If you would like to do a TeamViewer session I can take a look and see if there is anything that might have been overlooked. 73 Dave wo2x

Michael N3LI

Okay, now try the NR on the Flex. Really low though, like 1 or 2. 

Michael N3LI

Oh, and turn off any sound enhancements on the channels. They can sometimes wreak havoc 

Kevin Rich

Dave, 

I will have to get TeamViewer setup and would be fine having you take a peak if we can coordinate a time that works for both of us. 

73, 

Kevin

Roger_W6VZV

Wow, a noise floor of -140!  Mine is about -108 or so.  Noisy suburban neighborhood, I guess.

David Decoons, wo2x

I'll be available tomorrow except 1 p.m. to 3 p.m. Eastern (conference call).
Drop me an email at my call at ARRL dot Net and I'll send you my cell.

73
Dave wo2x

Kevin Rich

Thanks Larry and Michael.  I confirmed the settings and tried other DAX channels to no avail. I also confirmed there are no sound enhancements. 

Neal Pollack, N6YFM

You should not use, and should not need, NR or noise blanker on digital modes.
I am wondering if he got a bad circuit board or something?  But more likely audio level distortion getting in on the receive side.   I have an Icom 7300 and an SDR Play, and my Flex 6600 hears things the others can not.

Neal

Neal Pollack, N6YFM

You should not use, and should not need, NR or noise blanker on digital modes.
I am wondering if he got a bad circuit board or something?  But more likely audio level distortion getting in on the receive side.   I have an Icom 7300 and an SDR Play, and my Flex 6600 hears things the others can not.

Neal

George KF2T

i’ve also compared my 6600 with an RSP using the same MFJ splitter/switch. the RSP worked surprisingly well, but not better than the 6600, using side by side copies of WSJT-X on the same computer. 

Although it shouldn’t make a huge difference, check the sample rate on your DAX channel. 48000 is the best value in most cases. Using DIG-U, no audio shaping, fast or off AGC, and keeping WSJT-X “flatten” mode off should do the trick.

Bill W2PKY

What is the noise level on the 6600 with the antenna disconnected and preamp set to +8?
How about SDRPlay, is there a big difference between the antenna connected & disconnected?
If my noise level was 100 dbm I would not hear anything either.