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Technology advances in data transfer


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I was looking at the data transfer rates for planet earth's array of space junk (joke) and was surprised at the differences in speed of the data transfers currently running.

DSN Now (nasa.gov)

For example the Chandra was showing a DL data rate at 1.2Mbps, quite fast when you think about it although surprisingly the JWST is only 16 Kbps. Maybe this (JWST data rate) is simply throttled to that DL speed down to preserve bandwidth.  Also consider the old modem dial up speed usually ran at around 40-50 kbps. I am presuming this transfer rate for JWST is sufficient for the images it is taking and being it can run 24/7 without it's mum telling you she needs to use the dam phone 😅 it adds up over time to a fair lump of data. Not sure if my maths is right but around 1.3GB, still modest really.

But remember the next time you complain about your DL speed whatever that may be,  that voyager 1 is currently DL data at a rate of 160 b/ps. (It also takes circa 21 hours to get here)

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The Galileo spacecraft had an even weaker signal at first because of its failed antenna deployment, quote from the Wiki article:

Quote

the high-gain antenna was to have transmitted at 134 kilobits per second, whereas LGA-1 was only intended to transmit at about 8 to 16 bits per second. LGA-1 transmitted with a power of about 15 to 20 watts, which by the time it reached Earth and had been collected by one of the large aperture 70-meter DSN antennas, had a total power of about 10 zeptowatts.[97] Through the implementation of sophisticated technologies, the arraying of several Deep Space Network antennas and sensitivity upgrades to the receivers used to listen to Galileo's signal, data throughput was increased to a maximum of 160 bits per second.[98][99] By further using data compression, the effective bandwidth could be raised to 1,000 bits per second

so between 16-160 bits per second without data compression, yikes!

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25 minutes ago, bomberbaz said:

I was looking at the data transfer rates for planet earth's array of space junk (joke) and was surprised at the differences in speed of the data transfers currently running.

DSN Now (nasa.gov)

For example the Chandra was showing a DL data rate at 1.2Mbps, quite fast when you think about it although surprisingly the JWST is only 16 Kbps. Maybe this (JWST data rate) is simply throttled to that DL speed down to preserve bandwidth.  Also consider the old modem dial up speed usually ran at around 40-50 kbps. I am presuming this transfer rate for JWST is sufficient for the images it is taking and being it can run 24/7 without it's mum telling you she needs to use the dam phone 😅 it adds up over time to a fair lump of data. Not sure if my maths is right but around 1.3GB, still modest really.

But remember the next time you complain about your DL speed whatever that may be,  that voyager 1 is currently DL data at a rate of 160 b/ps. (It also takes circa 21 hours to get here)

If you scroll down on the data for JWST there seem to be multiple streams listed - so the upstream is 16kb/s, but there are two 28Mb/s and one 40 kb/s downstream signals 

UP SIGNAL

  • SOURCE JAMES WEBB SPACE TELESCOPE
  • TYPE DATA
  • DATA RATE 16.00 kb/sec
  • FREQUENCY 2.09 GHz
  • POWER TRANSMITTED 4.88 kW

DOWN SIGNAL

  • SOURCE JAMES WEBB SPACE TELESCOPE
  • TYPE DATA
  • DATA RATE 40.00 kb/sec
  • FREQUENCY 2.27 GHz
  • POWER RECEIVED -122.79 dBm (5.26 x 10-19 kW)

DOWN SIGNAL

  • SOURCE JAMES WEBB SPACE TELESCOPE
  • TYPE DATA
  • DATA RATE 28.00 Mb/sec
  • FREQUENCY 25.90 GHz
  • POWER RECEIVED -91.39 dBm (7.26 x 10-16 kW)

DOWN SIGNAL

  • SOURCE JAMES WEBB SPACE TELESCOPE
  • TYPE DATA
  • DATA RATE 28.00 Mb/sec
  • FREQUENCY 25.90 GHz
  • POWER RECEIVED  -95.70 dBm (2.69 x 10-16 kW)
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8 minutes ago, Gfamily said:

If you scroll down on the data for JWST there seem to be multiple streams listed - so the upstream is 16kb/s, but there are two 28Mb/s and one 40 kb/s downstream signals 

UP SIGNAL

  • SOURCE JAMES WEBB SPACE TELESCOPE
  • TYPE DATA
  • DATA RATE 16.00 kb/sec
  • FREQUENCY 2.09 GHz
  • POWER TRANSMITTED 4.88 kW

DOWN SIGNAL

  • SOURCE JAMES WEBB SPACE TELESCOPE
  • TYPE DATA
  • DATA RATE 40.00 kb/sec
  • FREQUENCY 2.27 GHz
  • POWER RECEIVED -122.79 dBm (5.26 x 10-19 kW)

DOWN SIGNAL

  • SOURCE JAMES WEBB SPACE TELESCOPE
  • TYPE DATA
  • DATA RATE 28.00 Mb/sec
  • FREQUENCY 25.90 GHz
  • POWER RECEIVED -91.39 dBm (7.26 x 10-16 kW)

DOWN SIGNAL

  • SOURCE JAMES WEBB SPACE TELESCOPE
  • TYPE DATA
  • DATA RATE 28.00 Mb/sec
  • FREQUENCY 25.90 GHz
  • POWER RECEIVED  -95.70 dBm (2.69 x 10-16 kW)

You are completely right of course, my error for not reading the screen more thoroughly.  I must say the 28Mb/ps seems a more reasonable rate and x2 as well.

Time for some reading on this, interesting!

Cheers

Steve

 

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Interesting video regarding data transfer rates of the JWST, Hubble and V1 here. It goes some way to explain the readouts received as shown from the link in my opening post.

 

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