Global Filter Modes
- Thread starter N8LHG
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I would personally look for the best signal quality as opposed to RSSI. Low "Noise" and "D-Error".
N8LHG
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You got my "thinking juices" going here. Just something to discuss and think about. I'm very much a "free over the air digital TV" viewer. Bear with me here, there is a method behind my madness. Now I have an antenna in my attic, and according to my TV "RSSI" display, I generally get four or more bars on the TV signal meter (Pretty useless since I have no idea what a bar of signal is on the TV). Generally, the TV picture is clean, and perfect UNTIL, there is any kind of windy weather. Doesn't have to be a strong wind, but even though I have a relatively strong signal, I get a fair amount of digital distortion due to what I assume is phasing type interference due to movements in foliage when the wind blows. The "RSSI" display stays fairly strong, but the picture pixelates sometimes to a point of not being worth watching. I assume the same kind of distortion happens with the digital radio signals we monitor. So, I assume we will see higher d-error numbers for the same reason, and since I'm using an ultra wide discone, that those issues will be exacerbated. I do notice, however, the stronger the signal (generally speaking), the less digital distortion or errors I experience. So, point being, sometimes its difficult to put my finger on what should be the priority, for both variables seem important.
Many thanks for the advice... This info along with some previous posts have combined to make this thread a wealth of info re: the SDS filters and the tuning threreof. I've even added D-Error and Noise level on my display alongside the RSSI graph and RSSI -dBm fields, in order to help me fine tune the filters in the future.
I can appreciate that the info you're sharing with the rest of us probably came as a result of much time experimenting and fiddling with various settings. I cannot thank you all enough.
Ubbe
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RSSI levels can be very misleading and the d-error and noise are a better indicator as those show the actual signal quality. Sat receivers always show signal strength and the quality of signal to noise in dB and you should always use the quality indicator when adjusting a sat dish.
SDS100 RSSI
/Ubbe
Thanks, Ubbe. Some very interesting data in the referenced link you provided--nice work.
Based on that info, I'm now experimenting with IFX on one "offending" site voice freq in the 450MHz range. After a few hours, it does seem to be helping--will have to watch that site over a longer period.
I also appreciate the info about the RSSI measurement... before adding the D-Error and Noise indications to the screen, the RSSI data was very deceptive and almost useless: digital signals sounded identical whether they came in at -60dBm or -105dBm--the beauty of digital radio, I guess. At least now, by watching the D-Error and Noise measurements, I can get a real picture of what's happening with the signal.
Many thanks for your assistance.
Others may have more definitive data, but within the 24 hours since digesting the info provided in this thread, my experience on WV state system (450-460MHz) has been:
Digital Error of 0, with spikes to 5-10 + Noise reading of mid-200s to low-500s = Best site reception
Digital Error of 5 to 10 with spikes to mid-30s + Noise reading of mid-300s to mid-800s = Good to Decent site reception
Of course, none of that takes into account RSSI which adds another variable to the mix, although I now understand that's less important as long as you can actually copy the signal. This thread discussion pretty much shows that since there are so many variables, it's difficult to put up a simple table that will define what your numbers should be on any given system. Case in point: even with a weak signal of -110 or -115dBm, I can easily copy a transmission as long as the digital error and noise thresholds are relatively low.
YMMV, but given what I've learned from the folks in this thread, I'm now tuning for a digital error rate of <10 and a noise measurement of <500 using the various global filters and IPX tools on our WV state system.
Hope that helps.
belvdr
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@lebrunmn Thanks for those figures. I'm scanning from a basement for the next few months, and with only the stock antenna. Knowing those figures, I was able to locate Wide Invert as the setting of choice for me: d-error < 5 and noise < 5000 now. It's not an ideal noise figure, but the clarity is much better and will likely be better when I get out the of basement.
So how long has it been since a Union rep has helped with anything related to the SDS series scanners?
belvdr
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Looks like 9/2/2021: Post by @JoeBearcat
They are being worked on from what has been posted
Ubbe
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DMR systems seem to get a pretty bad reception when digital errors goes above 5. Maybe it's different with P25. Noise values are mostly for evaluating analog systems as any kind of modulation like a datasignal will skyrocket the values. When there's just a silent carrier the Noise value will be the most true one and 500 are probably the highest you would want but will increase whenever anyone talks. But if read during a datasignal it can still be a good signal when Noise are up to several thousands as the high intensity data modulation will ruin the Noise detection.
/Ubbe
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Hey buddy, our paths don't cross that much anymore, I just got home now and I'm looking over radio reference. We've had quite an ordeal here in Bucks County PA, by far the worst storm we ever had in recorded history, including the hurricanes. But we had several devastating tornadoes.
Not going to get too involved here but I know that you know that I know exactly how the filters work and the proper way to apply them using Global for sampling, then returning Global to normal where it belongs and affects every object,
As has been said ad nauseam filters work differently for everybody for various different reasons like location, local RF interference or anything else you can come up with like a big building or tree nearby you LOL. Not that much different than ham radio and the knife's edge effect. It's always best to use real-time results like RSSI. Noise level and error rate. For those who say don't use the radio signal indicator oh, that depends on again your location and then noise that you have coming in that could affect the RSSI level. A lot of interference can certainly can increase your RSSI level. That's when it's important to use a very very indicative indicator, it's called... Your ear LOL. When doing conventional frequencies it's most important because you don't have a error rate.
Glad you are back online and safe the floods in Middle Tn were about 100 mile east of me. True and that is why Paul (UPMan) would only say they work different for each location.
baj76
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same here
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Thanks Buddy, one of the tornadoes just missed me and we had that warning on our phones and TV as the sirens were going off to seek immediate shelter in order to save your life. It'll be quite a while before we recover from this one.
Yes for some, no filter at all works best. When Paul introduced the filters on the first round to help with missed and clipped transmissions it was only normal, invert and Auto and there was a lot of clamor about making an option to leave them off if you wished to as if they were never introduced and he put out another update allowing you to leave them off. Later in another update he added the wide filters. It made a night and day difference on my counties tdma 700MHz Phase ll system that has one simulcast site and 26 towers which was having a lot of problems with the sds100. Invert filter applied to that one site was a miracle.
Really? From the guy that posted for a little while then left? If not, then from whom, please? I may have missed something that would change my skepticism?
Truth is, nothing has been done since Paul left us. -Zero- That was a huge loss.
And I'm not too confident there will be any forthcoming true "bug fixes" or "Firmware updates" like we used to get on a somewhat regular basis when Paul was here. Maybe they will sling some some "Shiny beads" at us, but I think they are in over their heads to be honest.
Would be nice to be ready for TDMA Control channel capability. I saw where a "Bearcat Representative" stated that " TETRA is still too sparse to be included", when there are systems in the US in use, and more being built out, yet there is a paid upgrade for "Provoice", which is disappearing as the months tick by.
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