News & Events
October 2018 – V3 modems ready for field testing
The design, construction and programming of the new V3 modems is complete. Dimensions, cost and power consumption are almost identical to the original “Nanomodems” (V2) but data rate is greatly increased to 640 bits/s, using a new orthogonal keyed spread spectrum modulation scheme, new MAC protocol features added and overall reliability is increased. The specification of the new devices in shown in the table below. Initial shallow sea water trials in Croatia and the Tyne estuary (up to 800m) have shown highly reliable ranging and exchange of test data packets so far. Larger scale trials will follow to establish maximum range and verify reliable operation in deeper water and with mobile platforms.
|
Supply voltage |
3 – 6.5V dc (5V or 6V supply recommended) |
|
Supply current (5V supply) |
Listening: 2.5 mA Receiving: 5mA Transmitting: max 300mA |
|
Acoustic frequency |
24-32kHz |
|
Acoustic source level |
~168 dB re 1uPa @ 1m |
|
Acoustic directivity |
Near omnidirectional |
|
Physical layer |
Aperiodic orthogonal code keying with BPSK modulation and error correction code. |
|
Acoustic data rate (raw) |
640 bits/s, unicast and broadcast data messages up to 64 bytes in length. |
|
Acoustic throughput (max) |
463 bits/s |
|
Addressing |
Up to 256 units (addresses 0-255) |
|
Ranging increment |
4.7 cm (c=1500m/s) |
|
Ranging variance |
~10 cm |
|
Maximum Range |
> 2 km |
|
RS232 interface |
9600 Baud, 8-bit, no parity, 1 stop bit, no flow control |
Last modified: Tue, 29 Jan 2019 09:57:54 GMT
