Documentation of the Franklin R910 for use as a secondary WAN link
Franklin R910 Device Specifications:
- Battery Life: 12 hrs usage / 27 hrs standby
- Number of Connected Devices: 10 Wi-Fi
- LTE Bands: 25, 26, 41 (aka "Sprint Spark") - hardware also supports 2, 4, 5, 12
- LTE-Advanced Carrier Aggregation
- LTE Performance Category 4 (Max Theoretical Speed: 150Mbps Down / 50Mbps Up)
- Wi-Fi Technology / Frequencies: 802.11 b/g/n - 2.4GHz , 802.11ac - 5GHz
- Dimensions: 3.46" x 2.62" x 0.47" / 3.5 oz
Antenna Notes:
- Oficially no antenna jacks.
- R910 has small black stickers covering 6 TS9 female connectors.
- These are around the perimeter of the device, not under the battery or label.
- the plastic surround of the device contains small antennas that are connected to pads next to these ports.
- removing that plastic surround shows ports that are labeled in pairs: 1708 MAIN, 1708 DIV, B41 MAIN, B41 DIV
- B41 ports do not appear to improve signal for operation where I am, since band 41 signal appears weak. These appear to be dedicated to band 41 since that uses very different frequencies and modes.
- WARNING: connecting to the B41 connections seems to put the device into an unstable state where it will then not reconnect to any network without a hard reset.
- Plugging an antenna into 1708 MAIN and 1708 DIV pairs does increase the signal (RSSI and RSRQ) on both bands 25 and 26.
- You can view which band is in use and signal values at Debug Engineering Hidden Page and the MSL isn't needed to access this page.
- To make connections with the TS9 straight barrel connectors I have, I needed to drill out plastic surrounds with 1/4 inch drill.
- Placing a $20 panel antenna on an old satelite dish and directing this at the tower increase signal strength and speed.
- Using the satellite dish limits the bands that are used because this is really useful only in the 2 GHz range.
Tethering Notes:
- Set the USB mode for tethering under USB mode in the webpst hidden page and change to mode "RNDIS + DIAG + ADB [Android]"
- Access to this requires use of the MSL for the device.
- This particular mode makes it look like a phone for tethering versus a dumb modem or usb stick.
- I connected the device to a super cheap GL.iNet mini router and configure it for tethering
- This tiny device runs openwrt and has some useful modules installed.
- Go to advanced settings in the GL.iNet and add the eth0 WAN port to the WAN interface so that usb and eth0 are bridged together
- Connect the upstream router to the GL.iNet WAN port and configure it to do DHCP
- This will get an IP from the r910 directly versus double NAT.
- Then MultiWAN can be configured on the main router.
- using another mode the setting name is "internet" and the APN is "r.ispsn"
Frequencies:
- Sprint uses LTE bands 25, 26, and 41.
- the modem is configured to use these in that prioritized order.
- the modem also supports 2, 4, 5, and 12.
- wikipedia has a listing of LTE bands
| E-UTRA band | Duplex mode | ƒ(MHz) | Common name | Included in (subset of) band | Uplink (UL) | Downlink (DL) | Duplex spacing | Channel bandwidths |
|---|---|---|---|---|---|---|---|---|
| 2 | FDD | 1900 | PCS blocks A–F | 25 | 1850 – 1910 | 1930 – 1990 | 80 | 1.4, 3, 5, 10, 15, 20 |
| 4 | FDD | 1700 | AWS blocks A–F (AWS-1) | 66 | 1710 – 1755 | 2110 – 2155 | 400 | 1.4, 3, 5, 10, 15, 20 |
| 5 | FDD | 850 | CLR | 26 | 824 – 849 | 869 – 894 | 45 | 1.4, 3, 5, 10 |
| 25 | FDD | 1900 | Extended PCS blocks A–G | 1850 – 1915 | 1930 – 1995 | 80 | 1.4, 3, 5, 10, 15, 20 | |
| 26 | FDD | 850 | Extended CLR | 814 – 849 | 859 – 894 | 45 | 1.4, 3, 5, 10, 15 | |
| 41 | TDD | 2500 | BRS / EBS | 2496 – 2690 | N/A | 5, 10, 15, 20 |
Sources:
FCC frequency info on the R910
Where to see LTE details on the R910
Where to change USB mode for tethering