XTB II Review

There are a few hundred BX24-AHT users who will tell you otherwise.

I know the BX24-AHT gave a relative signal level indication, but I don't recall anything saying what that readout meant in dBm.

Here is a cheap receiver with a true RSSI output:

Jeff

Since Bobby G. thought the prices for RF field strength meters were too high, I thought the goal was an inexpensive device that could be used to track down mystery X-10 RF signals. That's what I proposed.

The module you suggest costs quite a bit more than the one I suggested - more than the $15 I suggested as the total cost (and my guesstimate was a bit high). I couldn't get the OKW price quote to work but, from past experience, they mark these up over the RF Solutions price.

How do you propose to tune that module to 310MHz? It is not tunable.

I have one of those superhets somewhere but I really don't want to take the time to do a side-by-side comparison for this application.

The method I've used correlates quite well with distance between the transmitter and receiver - from a few feet to more than a hundred feet.

Since my method actually measures the depth of modulation (of the recovered baseband) it might be a better indicator than the RSSI output from the superhet receiver but it's hard to say without knowing exactly how they develop their RSSI voltage.

It's possible to increase the overall signal amplitude (at the linear output pin) by merely using a higher supply voltage for the receiver but the depth of modulation does not change nor is there an increase in effective range.

Received Signal Strength Indicator "RSSI output is often a DC analog level"

"Also, the specific RF receiver I mentioned has a linear output which can be used with an ADC input as an RSSI indicator. The RSSI of random noise will be low in comparison to a signal (as long as the signal is stronger than the random noise. You can use it as a rough Carrier Detect indicator."

but not with a plain reading of "there was a negligible difference between signal and no signal" which is what Dave writes today.

But no matter ;-)

... Marc Marc_F_Hult

Perhaps I missundrstood your earlier response, but I thought you had questioned my comment on using a module with a RSSI output. I just gave this as an example that there are inexpensive modules with a true RSSI output. I did not propose using this particular receiver for the X10 sniffer application. Even if it was tunable, its narrow bandwidth would still make it unsuitable for a sniffer.

Since I had an application that did need a good RSSI to maintain a table of access point signal strengths, I wondered if it is possible to get similar information from the received analog output. Wouldn't that be dependent on the data pattern itself?

I'm sure your method will work fine to locate a stuck transmit button.

Jeff

I don't recall questioning any such statement. I usually quote any statements that I'm commenting on or disagreeing with.

I really do not understand what you mean by "true" RSSI. I doubt the RSSI output of the receiver you reference is an absolute measure of signal strength in dBm, especially if the receiver has AGC. But without detailed specs it's hard to say.

Aside from any effects due to AGC, how is the amplitude of a pulse correlated with the data pattern?

I may have misunderstood this:

"I see they have recently started silk-screening "RSSI", on the module itself, for the "linear" output but this is misleading as it requires further processing to use it as RSSI."

I just wanted to point out that there are inexpensive receivers that do have a true analog RSSI output suitable for direct A/D, or to measure by a meter.

Not having done this myself, it would seem to depend on the data rate and how fast you can sample. Something like this would normally be secondary to the data itself.

Jeff

Ah! Your message with the RSSI reference hadn't shown up on my server at the time I sent my message. I was referring totally to the misleading label shown in the Wenshing photo.

When I was beta testing the XTB-I for Jeff, you were describing your new Insteon installation's progress and I really wondered if I had gone down the right path. Now that I've bought a few more XTB's, I'm absolutely sure I did the right thing for me.

As for your house, since you were building new, choosing Insteon wasn't nearly the issue it was for people like me faced with a housewide retrofit. You advanced the state of knowledge for the group by describing your installation and probably did end up with a more reliable system overall, so you choosing Insteon had lots of positives.

Once again I have near total reliability and it took me about five minutes of unplugging and replugging equipment to achieve it. Schweeeeeet! During the rare times I have the Monterey out to track some weirdness down, I am still stunned to see such large voltages reported, having become used to years of 70mv readings and less. It always reminds me of the line from "Aliens" when Bill Paxton says of the alien detector's chirping: "That's a big f__king signal!" Yes, indeed!

-- Bobby G.