Checking the signal strength
Signal Strength Considerations
While it may initially seem practical to check the signal strength of your connection before transmitting data, we strongly advise against this practice for several reasons. The dynamic nature of the Iridium satellite network and environmental variables make pre-transmission signal checks less effective and potentially misleading.
/* Example of checking signal strength */
AT+CSQ\r
/* Typical response showing signal strength */
+CSQ: <rssi>
Even if AT+CSQ returns a signal strength of 0, and you find yourself in a partially obstructed environment (such as next to a tall building), the RockBLOCK may still acquire a signal within a few minutes. We recommend testing in various locations with minimal obstructions from trees and buildings.
Why We Recommend Against Pre-Transmission CSQ Checks
- Rapid Satellite Movement: Iridium satellites move quickly across the horizon, typically passing from view within minutes.
- Variable Horizon: Common obstructions like mountains, buildings, and trees can drastically limit your horizon, reducing the effectiveness of a signal strength check.
- Response Time: The
+CSQcommand itself takes approximately 20 seconds to execute, during which time a satellite that was previously in a favorable position could move out of sight.
Given these factors, a satellite could have been in an ideal position to receive signals from your RockBLOCK, showing a strong connection momentarily, and then moved behind an obstruction or beyond the horizon by the time the CSQ check completes.
🏆 Recommended Approach 🏆
Instead of checking signal strength, proceed directly with transmitting your data using the +SBDIX command. Should there be any issue with the transmission, you can simply attempt to transmit again later. Importantly, you are only charged for successful MO (Mobile Originated) and MT (Mobile Terminated) transmissions, minimizing wasted credits. See the Adaptive Retry section for our recommended retry scheme.
/* Initiate transmission */
AT+SBDIX\r
/* Handle possible responses based on transmission success or failure */
This approach optimizes your use of the RockBLOCK and the Iridium network, ensuring efficient and cost-effective data transmissions without unnecessary delays.