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SANYO SRT-500P 24Hr Time-Lapse VCR



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. Itís a compact size -- equivalent to a Ďmidií-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 Ďused timesí, 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). Itís an adaptation of Sanyoís 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 tapeís 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 doesnít 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 itís 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 itís previous condition. The time and date are superimposed on the recording for the duration of the event,  an indicator flashes on the machineís front-panel display, and the event is logged in the machineís 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, itís 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 theyíre stored in a non-volatile memory



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 thereís 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, itís 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.



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 wouldnít have gone amiss, and would have broadened the machineís range of applications. The only general question mark concerns the usefulness of the 24 hour recording mode. Itís 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.



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                         ****                           




R.Maybury 1995 0211











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