Space Forum / Astronomy / September 2007

Can anyone verify that the designed scan rate of pictures on the 1977
Voyager Golden Record was 120 Hz?  If it was, do you agree the cover
has these 2 errors on it?

These won't cause problems in decoding the content, because the cover
specifies the first picture is a circle and any timing adjustments
needed to make this so will be applied to all pictures.  But still,
once those timing adjustments are made, the following two things will
be apparent to the receiving aliens.  How embarrassing for our race.

1) The top-right image on the cover shows a time of 8.34 ms (after
conversion from binary, multiplication by the hydrogen-line period,
and rounding) as the time of 1 scan line and *2 retrace lines*.  If
the intent was to indicate a 1/120 second sawtooth period, the left
duration marker should have been drawn one retrace-duration to the
right.

2) If the time indicated is meant to be 1/120 seconds (exactly 8 1/3
ms), then the binary value beneath it, resolved to as many bits as it
is, has a bit error.  The value shown on the cover is

101101001100000000000000 = 723*2^14 (exactly)

Multiplying 8 1/3 ms by the hydrogen-line frequency of 1420.405752
MHz, rounding to the nearest integer, and converting to base 2 results
in

101101001001110100101011 = 722.46*2^14 (approximately, but it should
round to 722)

So the 10th bit on the Voyager cover should be a 0, not a 1.  This
results in a time value very close to 8.34 ms instead of the ideal 8
1/3 ms.