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SANYO SRT-500P 24Hr Time-Lapse VCR
COPY
Time lapse video recorder technology moves at
a relatively slow pace, befitting the nature of the beast, and innovations --
not to mention new models -- are few
and far between. That makes the Sanyo SRT-500P doubly interesting, for it is
one of only a small handful of surveillance VCRs launched in the past twelve
months, moreover it incorporates several novel features.
Technically the SRT-500T is not a time-lapse
machine; it has two real-time recording modes, though the means by which it squeezes
8 or 24-hours of live video and sound onto a standard E-240 (4-hour) VHS tape is similar to systems
used on some longer-duration time-lapse machines. Short-duration machines such
as this are a comparatively recent development, the two principle applications
are surveillance camera recording, where premises are unattended for only relatively
brief periods, and daily event logging. Apparently the version of the SRT-500 sold
in the US is already proving very popular with casino operators and convenience
store owners.
The design and layout are fairly
conventional. It’s a compact size -- equivalent to a ‘midi’-sized domestic VCR
-- measuring 360 x 85 x 338mm. All of
the controls, apart from power on/standby and tape eject, are concealed behind
a hinged flap that runs the width of the front panel. The transport keys are
grouped together on the left side of the machine, beneath the tape hatch. The
rest of the buttons and switches are concerned with setting the recording mode
and speed, timer programming, alarm functions, tracking and picture sharpness.
On the back panel there are two BNC sockets
for composite video in/out, a pair of phono sockets for audio in/out, two minijack
sockets for a microphone and wired remote control, and a bank of screw terminals
for the alarm contacts. The fluorescent display panel shows deck mode and
status, real time tape counter, recording speed and alarm indications. The initial
set-up (adjusting time and date) is carried out using a simple on-screen
display. The time/date display can be moved to any part of the screen. In
addition the on-screen display also shows timer settings, alarm events and ‘used
times’, showing how long (in hours) the head drum has been in use, and the
total operating time of the machine.
The facility to record sound is a key feature
on this machine. Sound recording is not in itself unusual on 24-hour VCRs but
Sanyo have taken it one stage further with a feature called DMSS or digital
memory sound system. It allows the soundtrack of a 24 hour recording to be
heard at normal speed, when the recording is replayed at three times normal
speed (8-hour mode). It’s an adaptation of Sanyo’s digital view scan (DVC)
facility, fitted to a couple of their domestic
VCRs. The mono soundtracks on these machines can be heard, at normal speed,
even in the fast picture search mode, in either direction! DVC and DMSS work in
a similar manner, by digitising the audio output from the tape’s linear edge
track, storing it a memory buffer, then reading it out again, at the correct
speed (and the right way around, in the case of DVC). The system reads the
sound out in chunks, lasting a few seconds, so the soundtrack is intelligible
and keeps up with the fast tape replay speed.
The remaining features cover relatively
familiar ground. They include auto-repeat recording, daily or weekly program
timers, a built-in time/date generator and alarm recording. The two recording
speeds are 11.7 mm/sec and 2.59mm/sec respectively for the 8 and 24 hour modes.
The 8-hour recording speed is equivalent to the LP mode on a domestic VHS video
recorder, and tapes recorded on this machine can be replayed on dual-speed VCRs,
though the 500P doesn’t have a 3-hour SP replay function, so it cannot be used
to replay recordings made on other VCRs. The two recording speeds give
corresponding fast and slow-motion replay options, additionally it has cue and
review, reverse play, still and field step (forwards or backwards) modes.
Alarm functions are enabled by an external N/O
contact, the alarm connections are grouped together on a screw terminal block
on the back panel. When triggered the machine switches to the pre-set recording
mode, from stop or standby. If it’s already in the record mode it continues
recording. In the other two modes it will record for a period of 1 or 3 minutes,
or for as long as the alarm contacts are triggered (or a minimum of 5 or 15
seconds depending on the recording speed) after which it will return to it’s
previous condition. The time and date are superimposed on the recording for the
duration of the event, an indicator
flashes on the machine’s front-panel display, and the event is logged in the
machine’s memory. Alarm recordings can be quickly found using the alarm scan
feature, which seeks out recorded index signals on the tape, switching to the
replay mode from fast wind for five seconds at the beginning of each recording.
The 500Ps timer can be programmed to switch
the machine on to record -- at either recording speed -- for pre-set periods at
the same times every day, or for specific periods on particular days. In either
case the start and stop times are set using the on-screen timer display. Data
has to be entered into each field using cursor select and up/down buttons, it’s
not too bad for a single event but programming separate times for an entire
week can be quite time-consuming.
Security features include a simple control
lock, enabled by pressing a combination of control keys, and the clock has a
1-month memory backup. Following a power interruption the machine will
automatically revert to the previously selected mode; timer and alarm setting are protected as they’re
stored in a non-volatile memory
PERFORMANCE
There is very little difference in picture
quality between the two recording modes, though the slower 24-hour recording
rate 16.7 fields per second is evident in the slightly jerky playback. Actual
resolution is a little over 230 lines in the 8 hour mode, with comparatively
low levels of noise and dot interference. Colour fidelity is good. Still
playback is almost jitter free, the V-lock control manages to stabilise most of
the image but there’s still a very slight vibration at the very top or bottom
of the picture.
Inevitably the quality of recorded audio is quite
poor, though as it only has to be capable of handling speech and incidental
sounds, it’s perfectly adequate for this application. The DMSS system is very clever,
though the technology seems somewhat under
utilised, simply as a playback tool for 24-hour recordings. It would have made
more sense to use it over a wider range of replay speeds, like its domestic
counterpart.
OVERALL ASSESSMENT
Performance is good, it is relatively easy to
use, and the price seems fair. DMSS is interesting, though in its present form
it is of limited use. A 3-hour (SP) recording/replay facility wouldn’t have
gone amiss, and would have broadened the machine’s range of applications. The
only general question mark concerns the usefulness of the 24 hour recording mode.
It’s more than sufficient for overnight operation, but not long enough to cover
a weekend, which is where the real demand for a machine of this type lies.
PRODUCT ASSESSMENT
Design and design features ****
Circuitry and components ****
Ease of installation and wiring ****
Range and variety of functions ****
Accompanying instructions ****
Technical advice and backup ****
Value for money ****
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Ó R.Maybury 1995 0211
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