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The Model 740 is a small, cost effective Water Level Recorder, specifically designed for applications where the user simply requires an accurate record of water height, rather than the more sophisticated tide gauges that Valeport offer. Suitable for use in fresh or salt water, the 740 can be deployed for up to 2 years, dependant on the sampling rate, with instrument set up and data retrieval via PC software supplied. Alternatively, the system can be supplied with radio modules for real time data transmission. |
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Type : Vented strain gauge, with stainless steel
mounting bracket. |
| Range : Standard 10dBar (approx 10m), with 20m cable.
Other ranges and lengths available. |
| Accuracy : ±0.1% Full Scale. |
| Calibration: Held within logging unit. |
| Dimensions : 18mm diameter x 80mm. |
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| Logging Unit: |
Housing : Black anodised aluminium, waterproof to IP67
(0.5m for 30 secs), but system includes
transducer vent to atmosphere. The electronics
are sealed from the vent. |
Power : 4 "D" cells within housing. Alkaline cells provide
power for over 900 days at 20 minute sampling
with burst length of 10 secs. |
Memory : 128kbyte solid state, allowing over 65,000 data
points. Equivalent to over 900 days at 20 minute
sampling. New data file created every time unit is
switched on by user. |
Sampling : Raw data sampled at 4Hz and logged as
average over burst. Burst length is selectable
between 1 and 60 seconds. Cycle time is
selectable from 1 minute or from 5 to 1440
minutes (1 day) in 5 minute steps |
| Switching : Delay start time set by PC. Switch on by fitting
waterproof plug or comms lead to comms port. |
| Resolution : Data logged to 1mm resolution. Raw data
sampled at 14 bit (1:16384) resolution. |
| Comms: RS232 via 3m cable to PC, or via 1m cable to
radio unit. |
| Dimensions : Housing 47mm x 110mm x 235 mm. |
| Weight : 1.7kg (approx) including batteries. |
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| Radio: |
Frequency : Selectable frequency UHF synthesised radio
transceiver, operating in UK licence exempt band
(458.5 - 458.9 MHz). |
| Power output : Supplied as nominal 100mW peak output. |
| RS232 output : 4800 baud, 8,1,N. |
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| Aerials: |
| Transmitter : ¼ wave ‘rubber duck’ (standard, ~2km). |
3dB omni-directional (option, ~10km)
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| Receiver : 3dB omni-directional. |
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| Power input: |
| Transmitter : Takes power from Model 740, or from external
12vDC supply. |
| Current : 0.04mA sleep, 120mA receive, 410mA transmit. |
| Receiver : requires external 12vDC input |
| Current : 120mA receive, 410mA transmit. |
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| Transmitter Physical: |
| Materials : IP67 Black anodised aluminium box. |
| Size : 200mm x 200mm x 70mm. |
| Connectors : To antenna, Model 740 & external power supply. |
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| Receiver Physical: |
| Materials : Desktop style anodised aluminium box. |
| Size : 200mm x 180mm x 70mm. |
| Connectors : To antenna, 12vDC input & RS232 output. |
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