True, it is, but you can ignore most of it. Learning to read a datasheet (most have a very similar format) is a rewarding investment. No one is born knowing this stuff and I congratulate you for testing a theory and looking for the reasons it didn’t behave as expected.
For the VReg, this is the pinout
Although this datasheet is representative of xx1117 devices, it can only be relied on for chips of Ti manufacture.
The Specs on the PS+ claim 300mA at 5V. This works out to 450mA at 3.3V
The datasheet shows you should expect the Reg to start dropping out at 1.1V above the output voltage.
This says you need to at least 4.4V on the Pi’s USB Port.
Mine drop out 4.6~4.7V, so I guess they don’t have Ti chips.
Probably yes. (I say probably because I don’t have one to pull apart). The generic dongles are totally 3.3V. The RTL-SDR V3 can provide ~4.7V up the antenna feeder to power an external amp, but I think they use a boost reg from 3.3V
Not sure what is on the amp of the FA PS+, but I can’t see a second reg.
That is my experience.
Plenty of people here have reported no loss of performance with USB extension leads. I guess we are buying leads from the same place!
Pretty flexible I understand, with some outside help.
4,6V @ 1A. 4,3V with A of FA stick.
My measurements show that 5V input line to the stick cannot really be the problem. It does not make sense that the voltage is the problem, since it is not out of range of the LDO required input ánd the LDO still puts out 3,3V.
So as I was considering a 3 meter coax, my buddy reminded me to test my other 3 meter USB cable…and turns out, that one performs much better. Can do a more detailed test tomorrow including specs printed on the cable, but both (good and bad cable) are nothing special.
New theory is that the cable is just too low quality in general…while it was actually a branded one, a brand that normally does not deliver below average.
@geckoVN / @foxhunter
Interesting to read about your USB cable experiences. Definitely something going on with USB cables.
If you are seeing a decrease in message rate but not an outright dropout of data (I lost track of what you were arguing about with voltage regulators) then it’s not a voltage problem, the cable’s just coupling noise into the system. Ferrites may help.
I bought a bag of assorted clip-on ferrites and added them expecting no change but hoping to see an improvement.
What I observed was a drop in message rate.
I’ve been waiting for someone else to try to see the results.
I will try that again, as I tried it a few weeks ago.
Weird thing…looking in my project history, I see the best performance was achieved in very similar circumstances/setup with the USB cable that looked to be the problem yesterday. So it might have been broken meanwhile (which would really surprise me since it is a few weeks old, and I took care), or there is, once more, another force in play.
There are various in plane traffic that can account for a lot of variation. Maybe nothing is wrong or changed in you setup, just the traffic.
It’s the end of the summer, school started, less people in vacations… Less planes in the sky.
looking at my long term stats the deviation on some days is approx 10% either to increase of decrease.
As long as there’s no massive deviation from the average, it should be fine.
I did the mistake the other day by testing the antenna outdoors and i saw no improvement.
But then i checked the same timeframe the day before and exactly at this day the values were always going down.
So it wasn’t my setup but simply the time of the day. That brought me to the result to test an environmental change at least for several hours before rating it.
I solved that problem two or three years ago by setting up a separate system to use as a datum.
I put up an external antenna, added an inline amp and filter, a V3 receiver and a Pi.
Once i optimised that i haven’t changed it and do all my experimenting on other systems in parallel.
Regardless of the time of day, day of the week, season, phase of the moon etc, I can see what the effect of a change is in real time.
I don’t have to wait a day or a week to estimate if i have made an improvement.
Your datum can be a genetic dongle without amp or filter but the antenna really needs to be mounted outside in the clear so that other influences like bodies wandering around the room have no effect.
Yeah guys that is true, either compare by making quick changes and see big differences within seconds or minutes, ór compare over a much larger timespan of days/weeks.
There is no temperature sensor in rtl dongles as far as I’m aware. Raspberry pis have good I/O for adding things though, so you could always add a 1-wire sensor to measure it externally.
And if you can’t setup a reference system for real-time comparisons, you can always look at other nearby ADS-B users to see how you compare to their hourly trends.
