I wonder what HF sounds like from space- at the layer of skip. - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: September 28, 2017, 10:57:30 pm
content: Has anybody ever listened to say, the HF bands as we would with a shortwave radio, from space?Does the communications gear on the ISS have the capability to listen to HF? At that level, (around 400 km or 250 mi) they are basically at around the same height as the F2 layer in summer, and slightly above it in winter.... What effect would the ionospheric bending have on reception of digital modes?Also, I wonder how much of the junk I hear on HF bands is preventable emissions from devices around the world that aren't meant to be transmitting. One could ascertain that instantly from up in space!This analysis of these parameters from space actually seems like a quite worthy experiment that as far as I know has never been done..

author: bjcuizon
author_rank: Frequent Contributor
timestamp: September 29, 2017, 03:52:07 am
content: If HF waves bounce back to the earth via the ionosphere, can they escape out into space?

author: jh15
author_rank: Frequent Contributor
timestamp: September 29, 2017, 04:05:27 am
content: depends on the angle of reflection. If above the muf, maximum usable frequency it will not refract, and could hit the ISS.And they would get the signal, but others on the planet would not get it.I enjoy the major tech knowledge holes between ee and hams.A ham can fix a 50's radio.An ee would smell bacon burning with a soldering iron.A ham doesn't know what a computer without Windows is good for other than games and ham.Mac, well no new hardware there yet a long time.Never knew an ee that knew a tv. Tell about how reactance oscillators, sweep beam demodulators work.

author: CJay
author_rank: Super Contributor
timestamp: September 29, 2017, 08:42:33 am
content: I think you overestimate the effect of the ionosphere, I strongly doubt it would be a perfect reflector so there would definitely be HF signals 'escaping' out into space and that should make it possible to listen from the ISS for example, what I don't know is if anyone has ever done it (I've not done any research, they may well have and it could be very well documented somewhere)

author: PA0PBZ
author_rank: Super Contributor
timestamp: September 29, 2017, 10:22:11 am
content: Some of the Oscar amateur satellites had their downlink on either 15 or 10 meters, and I used some of them in the days. It always sounded a bit weird but that could be because you knew it was coming from space

author: jh15
author_rank: Frequent Contributor
timestamp: September 30, 2017, 03:30:52 am
content: There are hams aboard ask them.

author: vk6zgo
author_rank: Super Contributor
timestamp: September 30, 2017, 12:44:18 pm
content: Quote from: PA0PBZ on September 29, 2017, 10:22:11 amThe RS10/11 & RS12 of the 1990s also haduplinkson the 15m Ham band.

author: cdev
author_rank: Super Contributor
timestamp: October 01, 2017, 01:31:37 am
content: Even if "half" the signals get reflected before they get that high (say, its "winter" at that lattitude when the skip layer is lower..)and half not, thats only 3 db attenuation at the ISS's orbit height..Which sounds higher than it is..because believe it or not, if you know exactly where to look, and you look for the ISS within an hour or so after sunset (or before sunrise) with a decent pair of binoculars or a spotting scope or in my case, just a semi decent camera with a "long lens" and (good) optical image stabilization.. (not digital image stabilization) you can see the ISS and even make out its shape and sometimes if you are lucky even photograph it semi well. It keeps getting bigger!Quote from: CJay on September 29, 2017, 08:42:33 am

author: CJay
author_rank: Super Contributor
timestamp: October 01, 2017, 09:22:30 am
content: Quote from: cdev on October 01, 2017, 01:31:37 amI've seen it from my garden and other places many times without using binoculars or telescope, it was easily visible as a bright dot travelling right to left and it's an awe inspiring sight when you realise what, where and how...I've also used a pair of Minox binoculars which *just* about revealed the shape of the ISS but it could have been confirmation bias, on the same moonless evening while waiting for the ISS pass I could just about make out Jupiter and two moons .

author: Radio Tech
author_rank: Frequent Contributor
timestamp: October 02, 2017, 12:11:28 pm
content: Yep, the old Russian birds had 10 and 15 meter down links. I cut my teeth on them using a Kenwood TS-520 and Yaesu FT-221R. Also I still have a KLM Multi 2700 two meter all mode with a 10 meter receiver built in. Great fun back them and things were simple.