Beeps punctuated voice communications during Apollo missions due to specific technical protocols
the verdict
SUPPORTED
the evidence backs this
refutedsupported
the weight of evidence
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AS REPORTEDno primary record reached; this is what the reporting says
Historical sources report that the beeps heard during Apollo voice communications were Quindar tones used as an in-band signaling protocol to remotely turn ground station transmitters on and off.
# Why were there beeps punctuating the voice communications during missions such as Apollo?
Tags: nasa, apollo-program, radio-communication, audio
- Score: 30
- Views: 4652
- Answers: 1
- Answered: yes
- Asked by: Anthony X (18002 rep)
- Asked: 2014-06-08
- Edited: 2017-02-26
- Site: space
## Question
Voice communication between ground and spacecraft during missions such as Apollo seemed to be always punctuated by beeps. What was the origin of these beeps? Were they some sort of unavoidable artifact of the communications system in use? Did they have a purpose as a sort of automatic "Over!" as is customary in voice communication on simplex radio? Was it to help the communications equipment switch over between transmit and receive modes? Was it some sort of feedback occuring when both parties had their microphones keyed simultaneously?
## Answers
### Answer by pericynthion (score: 30 [ACCEPTED])
Those were called Quindar tones and they were used for in-band signaling in the ground communications network to key the transmitters at the ground stations. An "intro" tone is generated when CapCom in Houston presses his/her push-to-talk (PTT) button. This triggers the high power ampl
# What purpose serve the audible "bip" on apollo radio communications?
Tags: nasa, apollo-program, radio-communication, audio
- Score: 0
- Views: 1200
- Answers: 1
- Answered: yes
- Asked by: Manu H (3838 rep)
- Asked: 2017-02-26
- Edited: 2017-02-26
- Site: space
- Closed: closed
## Question
When looking at moonwalk videos, we can hear bips. What are those bips? Why are there bips? Do this bips still exist in nowaday space missions?
## Answers
### Answer by Fruchtzwerg (score: 3 [ACCEPTED])
These "beeps" are called the quindar tones (named after the manufacter Quindar Electronics, Inc).
These tones were used to simulate the action of the push to talk button. CAPCOM always had to push a button during communication. The first tone (2.525KHz / 250ms) triggers the ground station transmitters to send, the second tone (2.475KHz / 250ms) turns the transmitter off.
Quindar tones became very famous during the Apollo program but were used also before. Also the first Space Shuttle missions used them.
Today the quindar tones are not needed anymore because modern communication systems can carry multiple communication channels.
Quindar tones - Wikipedia
Quindar tones are the "beeps" that are heard during the American space missions. During the early days of the space program they were a means by which remote transmitters on Earth were turned on and off so that the capsule communicator(CapCom) could communicate with the crews of the spacecraft. It was a means of in-band signaling to simulate the action of the push-to-talk and release-to-listen (often referred to as PTT) button commonly found on two-way radio systems and walkie-talkies. However, even though the tones are no longer necessary with modern digital communication systems, they have been retained both for their historic aspect, and because flight controllers say they appreciate the audible cue of an imminent transmission.
## Rationale
When Mission Control(in Houston, Texas) wanted to talk to astronauts, the capsule communicator(CapCom) pushed a button (push-to-talk, or PTT) that turned on the transmitter, then spoke, then released the button. When the transmitter is local, this is easy to arrange: the transmitter is connected directly to the PTT button. But to stay in continuous contact with the astronauts as they orbit the Earth, or travel to
Everything we examined (3) — 2 independent sources
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