communication:examples
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| communication:examples [2008/06/07 18:23] – created rocketboy | communication:examples [2008/07/19 23:33] (current) – external edit 127.0.0.1 | ||
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| Assuming: | Assuming: | ||
| - | A Transmitter power of about 15dBm (about 30mW) – typical for most wifi routers. | + | * A Transmitter power of about 15dBm (about 30mW) – typical for most wifi routers. |
| - | Payload antenna gain is 0dBi (omni-directional) | + | |
| - | A Large ground station antenna of 24dBi (e.g. 3ft diameter dish) | + | |
| - | The slowest wi-fi speed (1Mbps) – which gives the greatest range | + | |
| - | 1Mbps receive sensitivity is between -91dbm (average) and -96dbm (very good) for | + | |
| - | a (borderline) 10% PER (Packet Error Rate) . | + | |
| This gives a maximum path loss of between: | This gives a maximum path loss of between: | ||
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| Which at 2.4GHz equates to a distance of between 32 and 63Km depending on receiver | Which at 2.4GHz equates to a distance of between 32 and 63Km depending on receiver | ||
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| ====== Practicality of using 2.4GHz FM TV from a balloon payload ====== | ====== Practicality of using 2.4GHz FM TV from a balloon payload ====== | ||
| - | Licence exempt FM TV modules running in the 2.4GHz band are readily available in the UK for CCTV application – what' | + | Licence exempt FM TV modules running in the 2.4GHz band are readily available in the UK for CCTV application – & what's more this band is explicitly allowed to used used in airborne TV applications. |
| Assuming: | Assuming: | ||
| - | A Transmitter power of about 10dBm (about 10mW) – all that is allowed. | + | * A Transmitter power of about 10dBm (about 10mW – all that is allowed). |
| - | Payload antenna gain is 0dBi (omni-directional) | + | |
| - | A Large ground station antenna of 24dBi (e.g. 3ft diameter dish) | + | |
| - | A receiver sensitivity of between -85dB (average) -91db (very good) for a (borderline) 10db video signal to noise ratio. | + | |
| This gives a maximum path loss of between: | This gives a maximum path loss of between: | ||
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| Which at 2.4GHz equates to a distance of between 9 and 18Km depending on receiver | Which at 2.4GHz equates to a distance of between 9 and 18Km depending on receiver | ||
| + | ---- | ||
| - | The use of bigger antenna dishes would result in longer distances – as a general rule – doubling the dish diameter will double the workable distance. | + | The use of bigger antenna dishes would result in longer distances – as a general rule doubling the dish diameter will double the workable distance. |
communication/examples.1212862983.txt.gz · Last modified: 2008/07/19 23:30 (external edit)