Security Installer

 BootLog.co.uk

HomeSoftwareArchiveTop TipsGlossaryOther Stuff

SANYO DTL-4800P DIGITAL VCR

 

COPY

The technology used for non-specialist surveillance video recording has always enjoyed a fairly close relationship with consumer VCRs. Most VHS and S-VHS time-lapse video recorders are not that far removed from their home deck cousins, indeed tapes made on the majority of surveillance VCRs will play back on domestic machines, after a fashion. More importantly, tapes recorded on one time-lapse VCR will usually play back on another manufacturer’s machine, which can be very convenient when a recording needed to be analysed or distributed for others to view. 

 

However, with the advent of digital recording a lot of the cosy cross-brand compatibility and flexibility seems to have been lost, though the gains, in terms of improved resolution and picture quality should not be underestimated. The Sanyo DTL-4800 digital video recorder is one of the first of the new breed of digital VCRs. It appears to be loosely based on the JVC’s D-VHS system (the D originally stood for ‘digital’ but now it means ‘data’), which made its consumer debut a couple of years ago. The key feature of the system is its ability to make very long duration recordings, or record several channels at once, with up to twice the resolution of standard VHS. Clearly that sort of capability has implications for the surveillance industry. D-VHS had a bit of a bumpy start in the consumer marketplace and to date only one JVC model has been launched, to a rather lukewarm reception. Many of its promised facilities, such as multi channel recording, have been omitted due to licensing and copyright problems.

 

The Sanyo DTL-4800 is not definitely not D-VHS compatible (we tried) nor will it play analogue VHS tapes, which seems a bit short sighted (backwards compatibility is a core feature of domestic D-VHS equipment). Indeed it’s likely that the only other tapes this machine can play are those recorded on another DTL-4800, the only visible connection it has with VHS is the tape cassettes it uses, though even that has to be a high-grade Super VHS formulation.

 

The basic line up of features includes 12 recording modes (12, 24, 48, 72, 96, 120, 168, 240, 360, 480, 720 & 960 hours, on a 3-hour tape), with audio recording possible in 12, 24, 48 and 72-hour modes. Within each speed setting it’s possible to specify frame (F) or field (H) recording mode and on the faster time lapse speeds, E (extended low), L (low) N (normal) and U (upper) quality modes, which in turn determines the amount of data allocated to each field. 

 

A video memory buffer enables pre and post alarm event recording (18 to 252 seconds, depending on recording mode). Resolution is claimed to be in the order of 520 lines, it can be remotely control by a PC using RS-232 or RS-485 serial communications, it has built-in timers, a range of programmable alarm record functions, a security lock and advanced tape management functions. We’ll take a close look at some of them in a moment.

 

It’s a fair old size, roughly twice the height of a typical VHS time-lapse VCR. The front panel is fairly innocuous with a cluster of large tape transport keys to the right of the tape-loading slot. There’s a display panel on the left side of the tape hatch and below that a hinged flap that opens to real a set of buttons and switches for controlling various secondary function and the menu-driven on-screen display. The back panel is equally straightforward. At the top there’s a row of connectors for video input and output (composite and S-Video) on BNC and mini DIN sockets, audio in/out (phono) and microphone (minijack). Below that there are two RJ11 sockets and a 9-pin D-Sub socket for serial communications. There’s another jack for an optional wired remote control unit, a DIP switch for setting up serial communications and a bank of screw terminals. These are for the alarm inputs and outputs, alerts (tape end, video loss etc.) and connections for VCR timing; external clock set trigger and communications. There’s also a small clip-in module containing a lithium backup battery for maintaining the clock and memory during power loss.

 

SETUP AND OPERATION

Pressing the Menu button behind the front panel displays the first of two main menu pages. Page one, item one covers language and time/date setting. Menu item 2 deals with on-screen displays, 3 is for setting audible warnings, 4 and 5 cover various tape handling and housekeeping functions (thread check, clog check, series recording etc.). Item 6 is for recording mode configuration (alarm mode, pre/post record duration, tape end action). 7 and 8 are used to set timer functions and number 9 is the Tape Management menu. On the second page there’s the serial communications setup menu, the alarm log, power/dew and used time information and the security lock setup. Menu options and selections are made using a group of buttons next to the menu key.

 

Menus 5 and 6 are largely responsible for how the machine behaves in day-to-day use, these include what happens when a tape is inserted (stop or record) and tape end actions (rewind, stop, eject and auto repeat). The timer can be programmed to record at specified times every day or only on certain days, additionally it has a ‘holiday’ mode and it can also be controlled from an external timer.

 

Tape Management is a key feature of the DTL-4800 and a useful spin-off from the use of digital technology. When enabled configuration data relevant to each cassette is recorded at the start of the tape. There are four main options: tape manager on/off, Protect Days, Record Pass Set, and Group No. Protect Days is used to stop a recording being overwritten for a set number of days, Record Pass Set puts a limit on the number of times a tape can be re-used and Group Number identifies an individual tape and assigns it to a nominated group.

 

Two or more DTL-4800’s can be connected together for series recording so that when one machine has reached the end of the tape (or less than 5% remains) the second or next machine takes over. Two VCRs can also be set up for continuous loop recording.

 

One of the first things most users will notice is how sluggish it is, compared with an analogue VCR. There is a 12 second delay from the point a tape is inserted to when the machine starts recording. It takes almost 15 seconds, after pressing the Stop button, before you can start playback, and a further 20 seconds, after pressing Play, before an image appears on the screen. Response times can be reduced by disabling the Thread Check function in menu 4 but the manual says this is not recommended, which suggest that it’s probably there for a good reason.  Another fairly obvious difference is the very modest assortment of replay facilities. Playback of long duration time-lapse recordings can be sped up by selecting a faster recording speed but it’s not possible to skim backwards or forwards through recordings at high speed. The best it can do is ‘search’ at around two or three times normal speed, or skip forwards (or backwards) with a frozen image on the screen, in two-minute bursts. Either way searching through a long recording for untagged (alarm) events can be a very tedious business.  

 

PERFORMANCE

Picture quality is astonishingly good and made all the more impressive in the 72 hour (and faster) modes by the accompaniment of relatively high quality audio. The claimed resolution of 520-lines is not very far off the mark, suffice it to say that unlike an analogue machine it will record just about all of the information coming from a camera or cameras, with no noticeable loss of definition. Images recorded in F and H modes (irrespective of speed) look exceptionally crisp. Colours are stable and accurate and it does a fair job of rendering subtle shades, such as skin tones. We suspect that on a lot of installations, if the effects of camera multiplexing and time-lapse recording are taken out of the equation, it will be almost impossible to tell the difference between live and off-tape pictures.

 

SUMMARY

Image quality is clearly the most important consideration and it’s fair to say that this machine wipes the floor with the current analogue formats. However, good though it is, digital tape technology in general and the DTL-4800 in particular still has a long way to go to match the convenience, flexibility and cost of analogue tape recording, but in critical applications where quality is paramount there is no doubt that many end users and operators will feel that it is a price worth paying.

 

PRODUCT SPECIFICATION

 

Power supply              230 VAC 50Hz

Weight                        6.8kg

Dimensions                 420 x 142 x 299mm

 

PSI RATINGS

 

Product                      

Product design             8

Build quality                           9

Ruggedness                            8

 

Operation                  

General functions                     8

CCTV functions                     8         

Ease of use                             7

Instructions                            8

Manuf. support                        ?         

Performance                           9

Video quality                          9

 

---end---

Ó R. Maybury 2000 2610

 

 


 

[Home][Software][Archive][Top Tips][Glossary][Other Stuff]


Copyright (c) 2005 Rick Maybury Ltd.

admin@rickmaybury.com