Model VR240 Audio Logging Recorder
January 2000
4-5
4-10. DEGRADATION.
With continued use, analog recorders degrade in an analog fashion. The frequency response
gets poorer, and wow and flutter increase. As the tape head wears, it becomes harder to align
the mechanism for proper performance, and audio quality suffers.
While digital recorders also physically degrade in an analog fashion, their performance doesn’t
suffer in the same way. Rather, the “error rate” increases. In most cases this doesn’t affect the
signal quality at all. Instead, the amount of tape used increases to prevent the reproduced
signal from losing integrity. Since the tapes have a built-in margin, this problem doesn’t become
evident until that margin is seriously encroached on. At that time, the drive must be realigned
and serviced. As with analog recorders, continued high performance requires periodic cleaning
of the tape heads.
4-11. TAPE
USAGE.
The VR240 uses technology similar to that used in video recorders—the tape speed necessary
for recording high-density information is obtained by using a rotating tape head. This increases
the information storage density many fold over a fixed-head machine. This, along with the
efficiency obtained by not wasting tape on unused channels, is responsible for the drastic
decrease in tape usage and tape storage requirements of the VR240.
In an analog recorder, each channel is assigned to a separate track on the tape. The same
amount of tape is used whether one channel is active or all channels are active. That’s a lot of
waste.
The VR240, however, “multiplexes” all channels onto a single data track. When there is no
active signal on a channel, there is no data for that channel on the tape. Therefore, if only two
channels are active, an 8-channel VR240 will use tape only one fourth as rapidly as an 8-
channel analog recorder. This, along with the rotating head technology, digital signal
processing, and the nature of the tape itself, is what allows us to record so many hours on such
a small tape.