Quindar Tones: the beeps heard in recordings of astronauts in space
1–10 of 63 posts
Re: Quindar Tones: the beeps heard in recordings of astronauts in space
#2I know them as "roger beeps" from CB radio terminology.
Re: Quindar Tones: the beeps heard in recordings of astronauts in space
#3Does anyone know why they picked frequencies quite close together for the in/out tones (2525Hz/2475Hz) when the pass band for telephony was much wider?
Re: Quindar Tones: the beeps heard in recordings of astronauts in space
#4Does anyone know why they picked frequencies quite close together for the in/out tones (2525Hz/2475Hz) when the pass band for telephony was much wider?
so they could be removed with a single notch filter
Re: Quindar Tones: the beeps heard in recordings of astronauts in space
#5Does anyone know why they picked frequencies quite close together for the in/out tones (2525Hz/2475Hz) when the pass band for telephony was much wider?
Based on some quick Googling, it looks like the pass band they used for voice (at least for Apollo) was 300Hz to 2.3kHz. Assuming that filtering was being applied in the audio gear and the RF side of things was a bit more permissive, that would allow them to keep the control tones outside the range of any vox transmission.
Re: Quindar Tones: the beeps heard in recordings of astronauts in space
#6Does anyone know why they picked frequencies quite close together for the in/out tones (2525Hz/2475Hz) when the pass band for telephony was much wider?
-Probably placed at the upper end of the passband so you could use a single high-pass filter in front of the detector to get rid of any noise on the line, easing detection.
Also, if you wanted to remove the tones from the passband for some reason or other, you could do that with a single notch filter if the tones were sufficiently close.
Re: Quindar Tones: the beeps heard in recordings of astronauts in space
#7> if NASA wanted to send control signals like transmit on and off, they’d need to run a whole parallel set of wires, which would be expensive. So, they came up with a solution: use the same lines for control signals as well!
It really seems that in earlier years, when resources were limited, people really used their ingenuity far better than today.
Maybe I have rose tinted glasses, but the level of creativity and cleverness seen in old solutions to problems/challenges just blows my mind all the time.
Re: Quindar Tones: the beeps heard in recordings of astronauts in space
#8> if NASA wanted to send control signals like transmit on and off, they’d need to run a whole parallel set of wires, which would be expensive. So, they came up with a solution: use the same lines for control signals as well! It really seems that in earlier years, when resources were limited, people really used their ingenuity far better than today. Maybe I have rose tinted glasses, but the level of creativity and cle…
Inband signalling was the way long distance trunk lines worked back in the MF signalling days decades before ISDN D channels and SS7 and all that.
A fun topic to google for is what and how the 2600 Hz signal worked.
Re: Quindar Tones: the beeps heard in recordings of astronauts in space
#9> if NASA wanted to send control signals like transmit on and off, they’d need to run a whole parallel set of wires, which would be expensive. So, they came up with a solution: use the same lines for control signals as well! It really seems that in earlier years, when resources were limited, people really used their ingenuity far better than today. Maybe I have rose tinted glasses, but the level of creativity and cle…
Inband signalling was the way long distance trunk lines worked back in the MF signalling days decades before ISDN D channels and SS7 and all that. A fun topic to google for is what and how the 2600 Hz signal worked.
Didnt some guy figure out how to get free phone calls using a cheap whistle from a cereal box :-)
Re: Quindar Tones: the beeps heard in recordings of astronauts in space
#10Earlier quoted context omitted.
Inband signalling was the way long distance trunk lines worked back in the MF signalling days decades before ISDN D channels and SS7 and all that. A fun topic to google for is what and how the 2600 Hz signal worked.
Didnt some guy figure out how to get free phone calls using a cheap whistle from a cereal box :-)
Captain Crunch!