tomfanning

5 ms·

1.
by tomfanning 1y ago
> it's rare you hear one that heavy any more With respect, this is nonsense.
2.
by tomfanning 2y ago
In SSB there is no carrier transmitted. Two SSB stations on top of each other sounds exactly like two microphones mixed.
3.
by tomfanning 3y ago
DIY: slim jim, J pole ( https://m0ukd.com/calculators/slim-jim-and-j-pole-calculator... ) or quarter wave ground plane ( https://m0ukd.com/calculators/quarter-wave-ground-plane-ante... ). A slim jim m
4.
by tomfanning 3y ago
That’s a pretty narrow perspective. From both the perspective of HF and VHF/UHF. For HF there’s all sorts of digital stuff going on. Check out FreeDV for a Codec2-derived digital voice mode. We are also doing packet radio (yes, AX.25,
5.
by tomfanning 3y ago
Speak to a specialist about the Stretta procedure. Application of RF energy to the lower esophageal sphincter in a short outpatient procedure. More effective than PPIs, but less so than fundoplication, which is much more invasive and perman
6.
by tomfanning 3y ago
Even ignoring the impedance mismatch, loss in typical 75 ohm coax at 2.4GHz is going to be something like 0.5dB per metre. Far worse again at 5GHz. That's going to add up quickly.
7.
by tomfanning 4y ago
Someone once told me "Friends don't let friends use Fritzing".
8.
by tomfanning 4y ago
An entirely sensible one which prohibits you from preventing an emergency call being made in case of fire, injury, crime etc.
9.
by tomfanning 4y ago
Wheel successfully reinvented :) Nothing stopping you setting up a whole AX.25 network between multiple machines using Dire Wolf [1] and the built-in AX.25 [2] (a derivation of X.25) support still in the Linux kernel. You get a proper netwo
10.
by tomfanning 4y ago
It would be better for everyone if this were deleted.
11.
by tomfanning 5y ago
PSA: Pi 4 + M.2 SATA SSD + USB3 adapter is blisteringly fast. No micro SD card needed any more. Runs Ubuntu x64 and Docker. Even better with a heat-dissipating case with an integrated M.2 SATA port in the bottom, like the Argon ONE M.2. I u
12.
by tomfanning 5y ago
Who specifically is "their"?
13.
by tomfanning 5y ago
For every engineer on six figures there will be many many of them on five figures. We read about six-figure engineer salaries because people write about them. $100k is well above the US median. I don't think there should be an absolute
14.
by tomfanning 5y ago
Yes but. I'm looking right now at a mtr (traceroute) screen from a rural fibre-to-the-premises broadband connection in Lancashire, north-west UK, achieving 2.5ms RTT to Manchester (the nearest major city, ~60km) and 8.5ms RTT to London
15.
by tomfanning 5y ago
Trans-oceanic flights go far beyond the VHF radio horizon to land so routinely use HF radio. It's not a backup, it's the norm. Example: https://www.iaa.ie/air-traffic-management/north-atlantic-com... "Hu
16.
by tomfanning 5y ago
Isn't this completely standard practice now?
17.
by tomfanning 5y ago
Many of the red areas I see on the map, particularly in France, are fairly obviously where someone's been running a TomTom while on a train or a boat. Of course that's not going match OSM roads. I'm a little surprised this is
18.
by tomfanning 6y ago
Europe is a continent.
19.
by tomfanning 6y ago
Not over licensed RF links in most countries, unless you publish the private key.
20.
by tomfanning 6y ago
The experience operating sats is very different depending on where you are on the globe. Advice that's okay in one place may be bad advice in a different location. One final heads-up, the vertical antennas typically fitted to vehicles
21.
by tomfanning 6y ago
Fancy-pants cross-band full duplex can be achieved with two £15 Baofeng UV-5Rs and a DIY duplexer with about 2 components on it (or just two antennas on one boom). That's my setup - I'm not better equipped than that.
22.
by tomfanning 6y ago
A second-hand Kenwood TH-D7 is an alright choice.
23.
by tomfanning 6y ago
Dual watch, or full duplex? My decades-old FT-470 can do true full duplex too, but it's less common in current radios. Just dual watch now.
24.
by tomfanning 6y ago
Kenwood TH-D7
25.
by tomfanning 6y ago
Yes, you absolutely do need true full duplex to (a) know you're getting in, (b) not step on anyone else, (c) know when you're being stepped on, all of which are really required to operate effectively and courteously.
26.
by tomfanning 6y ago
Yeah, it's a lightly modified Kenwood mobile VHF/UHF set typically used in a car. Model D710GA. Stock it's a 50W radio, though can be run at 5W. Cube sats have around the hundreds of milliwatts. So yes, much higher power tha
27.
by tomfanning 6y ago
Sounds like you're already on it, but anyone who is thinking of trying, (1) make sure you are correctly licensed, (2) make sure you only transmit while you can clearly hear the downlink, and (3) make sure you are listening to the downl
28.
by tomfanning 6y ago
For listening, a QFH antenna is ideal for LEO objects. It's typically made of copper pipe or the braid of stiff coax.
29.
by tomfanning 6y ago
Short answer - by one or two of the smallest steps on a typical handheld, starting above the nominal frequency and ending below it. A bit more than that for UHF downlinks.
30.
by tomfanning 6y ago
A 90 degree pass (overhead) is around 10 minutes. And obviously for radio, it doesn't need to be visible (reflecting sunlight), just ~above the horizon.

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