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Author Topic: EW 500 G4 RX Diversity Circuit Operation  (Read 1051 times)

Russell Ault

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EW 500 G4 RX Diversity Circuit Operation
« on: March 08, 2020, 04:56:50 PM »

According to the spec sheet, the EW 500 G4 RX is "true diversity", but does anyone know how its diversity circuit actually works? Is it just switching between signals, or is it blending A and B to some extent?

The reason I ask is because I recent had some very intermittent interference on a channel. Three very short bursts of noise came through the RX. When I reviewed the recording (we're using WaveTool), there was a significant drop in RF signal on the A-side of the RX that matched up with the noise bursts, but the receiver was supposedly using the B-side (with perfect signal strength) the whole time.

Is this a case of the diversity circuit mixing signals from both sides and picking up noise from the dropping A-side, or am I barking up the wrong tree?

Thanks!

-Russ
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Ike Zimbel

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Re: EW 500 G4 RX Diversity Circuit Operation
« Reply #1 on: March 08, 2020, 06:05:01 PM »

According to the spec sheet, the EW 500 G4 RX is "true diversity", but does anyone know how its diversity circuit actually works? Is it just switching between signals, or is it blending A and B to some extent?

The reason I ask is because I recent had some very intermittent interference on a channel. Three very short bursts of noise came through the RX. When I reviewed the recording (we're using WaveTool), there was a significant drop in RF signal on the A-side of the RX that matched up with the noise bursts, but the receiver was supposedly using the B-side (with perfect signal strength) the whole time.

Is this a case of the diversity circuit mixing signals from both sides and picking up noise from the dropping A-side, or am I barking up the wrong tree?

Thanks!

-Russ
Perhaps the "B" side was actually noise, which you heard when the "A" side dropped out? Just a wild-assed guess... Was the channel close to either a digital carrier, or a DTV channel?
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~Ike Zimbel~
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Henry Cohen

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Re: EW 500 G4 RX Diversity Circuit Operation
« Reply #2 on: March 08, 2020, 08:31:01 PM »

According to the spec sheet, the EW 500 G4 RX is "true diversity", but does anyone know how its diversity circuit actually works? Is it just switching between signals, or is it blending A and B to some extent?

In the analog world, "true diversity" in "marketing speak" means two independent antennas and receivers. Depending on the circuit design (read that as price point) there's a comparator circuit comparing every XmSec the audio outputs of each receiver and, in the better designs, the RSSI of each. The comparator selects the best audio/RSSI according to the OEM's proprietary algorithm and sends that audio to the output.

Blending of RF in the analog world can only really be done in the time domain: If the signals arrive at each antenna within +/-X degrees they would be combined; more than X degrees out of phase and the stronger RSSI is used. (This was one of Lectrosonics' claim to fame with their 200 series "Roto-Phase" circuit.)

True combining of signals (Axient digital and most higher end RF video systems), called Maximum Ratio Combining, can only really be done at a price point and form factor for the entertainment industry in the digital domain. (IIRC when early satellite communications were still mostly analog, there was a broad time span combining of the satellite signals among the earth stations, but the latencies were huge, relatively speaking, and the equipment filled a room.)
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Re: EW 500 G4 RX Diversity Circuit Operation
« Reply #2 on: March 08, 2020, 08:31:01 PM »


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