We had a number of questions at our Digi XLR PRO webinar and unfortunately there was not enough time to answer all of them. We’ve combed through the submitted questions and have put together some of the most commonly asked questions in this post, including results from our field testing.
Video: Is it possible to send live IP video on this system?
Yes, in IP bridging mode the radios are capable of streaming rates in excess of >1 Mbps which is sufficient for many video streaming applications. We have tested by streaming YouTube videos and Netflix through the radios in a point to point link.
Security: How does the Digi XLR PRO address data security?
The XLR Pro radios support 128 bit AES encryption. By default, encryption is always used, but the key is never displayed. If you enter a new encryption key, the key must match on all devices on the network.
Power Consumption: Can this be used for battery powered remote devices?
Receive Current: 300 mA @ 9 V; 230 mA @ 12 V; 120 mA @ 26 V
Transmit Current: 950 mA @ 9 V; 840 mA @ 12 V; 400 mA @ 26 V
The packaged radio is not designed with low current draw as the primary concern. With an appropriately sized battery/solar panel combination it may be successfully deployed in non-mains powered applications. It is the intent to make low current draw much more important in the OEM module design.
Punch2 vs FHSS: How does Punch2 Technology compare to the more common FHSS?
Many radios in the unlicensed 900 MHz band use frequency hopping spread spectrum (FHSS), which transmits data at multiple frequencies using a hopping pattern. The transmitter hops among different frequencies to combat fading and interferers. The channels may have different levels of interference and fading, allowing communication on some channels but not others. The diversity of operating at multiple frequencies results in improved communication reliability.
Conversely, Punch2 Technology uses a wide bandwidth for each bit of information that is transmitted. With this method, each bit of information leverages frequency diversity across the band—as opposed to the hit-and-miss approach of FHSS with individual packets. Compared to FHSS, Punch2 Technology provides superior resistance to signal fading without resorting to frequency hop synchronization. It also requires no beacon frames or time synchronization frames, resulting in decreased network traffic. The advantages of Punch2 Technology arise from the characteristics of the chirp signal as well as several digital-signal-processing techniques that enhance performance and reliability.
Network Topology: What type of network configurations does the XLR PRO support?
The radios support 2 types of transmissions:
Unicast - To transmit to a specific radio:
- When using transparent mode, set DH:DL to the SH:SL of the destination radio.
- For API mode, set the SH:SL address in the 64-bit destination address field of the API frame.
Broadcast - To transmit to all radios:
- For transparent mode, set DH:DL to 0x000000000000FFFF.
- For API mode, set the 64-bit destination address fieldto 0x000000000000FFFF
- The scope of the broadcast changes based on the delivery method chosen.
The radios do not support Mesh but do support repeated serial packets up to 4 hops. We suggest reading the XLR PRO networking methods chapter of the User guide starting on page 30 for more details.
Field Test Results
During the webinar we shared some of the results from the field test we performed with the Digi XLR PRO and other long range 900 MHz radios. We have more details in this report. Click here to download the official results.