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 The 'Desense' and latency parallels

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A5H5ATAN1C
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Call Sign : 26-CT-4145
Posts : 85
Times Thanked : 1
Join date : 2021-06-03
QTH or Location : Chatham, Kent
Equipment Used : Includes :- AT-878UV, FT474Gx, AT-5555N, FT-818, DNT M40 (RT Factory, Manpack config), Midland Portapack, IC-211E, TS700G, TS2400, MAXCOM 16E, unbranded 40 channel Japanese 49 & 2.4Ghz transceivers (supposedly Uniden, but unlikely)
Age : 52

The 'Desense' and latency parallels Empty
PostSubject: The 'Desense' and latency parallels   The 'Desense' and latency parallels Icon_minitimeWed Jun 09, 2021 12:30 pm

Now whilst the reference examples I'll use are based on say dual WiFi, WiFi+a.n.other wireless, dual BT and any combo off in close antenna setup and close 'station' use, it's also relevant to radio usage 'desense' and for TG ops (legit or otherwise, as physics makes no distinction) it's a notable issue where it can and will, in different installation extents and degrees, be a cause of why you may find in radio TG you get horrible error rates sometimes and even with true high gain antennas (by true, I mean actual dBd  measured characteristics not the pseudo BS active gain stuff).

So in essence it's fundamentally the same cause or rather an effect of proximity and contention that's even more notable indoors at SHF where networking wireless links often and mostly exist.  So it's as commonly an effect with any close coexisting TxCr and RxCr combinations.

No.1 close proximity cause of LQ links and stuttered DV (digital voice and digital video incorporating) and network/TG narrowband contention is the combined effect of proximity (each Tx swamping each and every close Rx in the setup) and when you've got WiFi and BT banging away near each other, plus a.n.other type operating on the higher and lower ISM segments, they'll each cause a desense in some degree on RxCR's nearby and distinctly whilst the field density is q.0 plus (and you can bet it will be).

You can tame it to degrees with careful use of inline filters (I'm assuming WiFi/BT etc with plug in antennas where patch cables may be used to reposition/align for best seperation) at an inherent insertion loss, by repositioned equipment and antennas, even by cracking back the mW level outputs to a minimum as best you can and maintain comms.  But ultimately, you can only get a minimal real impact without separation and filters and ... *cue horror music* surgery.

I've used all the above methods, in all manner of applications and even employed cavity filters in cascades where needed, but reducing the fields generated, improving the 'cage' that's the equipment casing and even fabricating new screening cans etc has become necessary to really refine the impact of such problems.

Even, notably with the GHz territory equipment which can incorporate some kinds of digital voice mode HH transceivers as well, even your beautiful work of art titanium 'phile' case still has weakness that compromises it's Faraday cage effectiveness.  You see, the slots and gaps are lovely apertures and likewise any extrusion structures making up the internal framework, it's SHF's best escape going and in the right combo, has a passive gain beam forming low loss type path.  Even the plastic bits are not immune as they still leak, but at SHF they are more attenuator than leaks, but for close proximity purposes, what passes through plastic and perspex and PVC isn't as minimal as it's inherent attenuator characteristics would lead you to suspect.

So, and it's a minefield of factors in it's own right starting with interconnection line attenuation consequences, it's better to remount all your digital transceiver modules (hotspot and network adaptors etc) separately cased so the inherent leaked EM fields that collide are minimalised.  This may involve coax patch leads and new connectors but since it probably will require recasing as well, upgrading the RF connectors and using HQ screened interconnects internally isn't a bad move even if It carries it's own complications.

But ultimately, you'll only offset so far - but if you manage to improve or get SQ's near or within optimal ranges link wise and ultimately reduce the error count demonstrated by an RSSI check, you'll have made a big step even if it looks like you got little tangible results you can hold and admire and show off - but if you've improved the EMC by 1%, it'll pay dividends even if it's only because you actual got around to reducing an annoyance that keeps having a fix pushed under the proverbial mat.

As with most things radio, it's the intangibles that have the most influence of the purity, quality and general performance of any radio setup and combo of.

Take a look at how much planning and effort and testing that goes into even the most basic repeater commercial setup, bearing in mine the gear probably shares a mast and site with other user services thanks to geography and other factors EMC related these days, and you'll grasp the significance of what I've scratched the surface of.

I won't even begin to detail (in tutorial/how-to form in additional posts) what extents and degree and methods I used to maximize EMC and clean up the inherent garbage of lots of close prox wireless gear, as I'd rather not spend that much time reinventing the wheel and quite honestly, in piece meal form, there's loads of insight to it scattered over the net already - stuff that wasn't there back in the day.

So good luck, keep it clean and may your error rates be minimal and bps be optimal.
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