# Custom Channel Bandwidth **URL:** \ **Category:** Hardware Questions and Recommendations\ **Created:** [January 3, 2019, 6:07pm UTC](https://forum.openwrt.org/t/custom-channel-bandwidth/28255 "2019-01-03T18:07:49Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![omega](https://forum.openwrt.org/letter_avatar/omega/32/5_5575768a8748004e209b776fc1b2916d.png) [@omega](https://forum.openwrt.org/u/omega)\ **Post date:** [January 3, 2019, 6:07pm UTC](https://forum.openwrt.org/t/custom-channel-bandwidth/28255/1 "2019-01-03T18:07:49Z")
Typically, the channel bandwidth value is pre-defined by the standard. Possible values are 5, 10, or 20 MHz for example. Is there any 802.11 wireless device (compatible with OpenWRT) capable of configuring a custom channel bandwidth? For example, a 6.25 MHz channel bandwidth value. Thanks! ---
**Author:** ![jeff](https://forum.openwrt.org/letter_avatar/jeff/32/5_5575768a8748004e209b776fc1b2916d.png) [@jeff](https://forum.openwrt.org/u/jeff)\ **Post date:** [January 3, 2019, 7:39pm UTC](https://forum.openwrt.org/t/custom-channel-bandwidth/28255/2 "2019-01-03T19:39:37Z")
Frequently asked, especially by those coming from a world with non-standard, vendor-proprietary hardware. > [@5 Mhz bandwith option?](https://forum.openwrt.org/t/5-mhz-bandwith-option/3615/2): > > Sub-20MHz channels are only configurable via debugfs and are not supported by LuCI or any of the standard Linux wireless utilities. Try echo 5 \> /sys/kernel/debug/ieee80211/phy0/ath9k/chanbw on both sides of a working p-t-p link. ---
**Author:** ![omega](https://forum.openwrt.org/letter_avatar/omega/32/5_5575768a8748004e209b776fc1b2916d.png) [@omega](https://forum.openwrt.org/u/omega)\ **Post date:** [January 4, 2019, 11:39am UTC](https://forum.openwrt.org/t/custom-channel-bandwidth/28255/3 "2019-01-04T11:39:32Z")
Thanks Jeff! Looking at: [https://openwrt.org/docs/guide-user/network/wifi/basic](https://openwrt.org/docs/guide-user/network/wifi/basic) I found the parameter: _chanbw_ (integer) Specifies a narrow channel width in MHz, possible values are: _5_ , _10_ , _20_ My case is even more special, because I'd like to be able to set a different value from the pre-defined ones and even non-integer values like 6.25 MHz. I know it is possible since this OpenWRT-based product has this feature: [https://doodlelabs.com/products/industrial-iot-radio-platform/](https://doodlelabs.com/products/industrial-iot-radio-platform/) It says: "Software defined channel size of 3~40 MHz for efficient re-use of spectrum", and I know it can be continuously (with non-integer values) adjusted. But I don't know which hardware is used. Hope someone help me finding this answer. Regards! ---
**Author:** ![mbo2o](https://forum.openwrt.org/user_avatar/forum.openwrt.org/mbo2o/32/5465_2.png) [@mbo2o](https://forum.openwrt.org/u/mbo2o)\ **Post date:** [January 4, 2019, 1:52pm UTC](https://forum.openwrt.org/t/custom-channel-bandwidth/28255/4 "2019-01-04T13:52:03Z")
I think you miss read the data sheet. For wifi it only supports 5,10 and 20Mhz channel width. The 3-40MHz probably refers to other radio modules not wifi. > **[Doodle-Labs-Smart-Radio-RM2450-Datasheet.pdf](https://doodlelabs.com/wp-content/uploads/Doodle-Labs-Smart-Radio-RM2450-Datasheet.pdf)** > > 314.21 KB ---
**Author:** ![Pippo](https://forum.openwrt.org/letter_avatar/pippo/32/5_5575768a8748004e209b776fc1b2916d.png) [@Pippo](https://forum.openwrt.org/u/Pippo)\ **Post date:** [January 4, 2019, 4:18pm UTC](https://forum.openwrt.org/t/custom-channel-bandwidth/28255/5 "2019-01-04T16:18:09Z")
> **[ISM band](https://en.wikipedia.org/wiki/ISM_band)** > > The industrial, scientific and medical (ISM) radio bands are radio bands (portions of the radio spectrum) reserved internationally for the use of radio frequency (RF) energy for industrial, scientific and medical purposes other than telecommunications. > Examples of applications in these bands include radio-frequency process heating, microwave ovens, and medical diathermy machines. The powerful emissions of these devices can create electromagnetic interference and disrupt radio communication u De... should I smell a rat ? I mean how big the UAV can be ? ---
**Author:** ![omega](https://forum.openwrt.org/letter_avatar/omega/32/5_5575768a8748004e209b776fc1b2916d.png) [@omega](https://forum.openwrt.org/u/omega)\ **Post date:** [January 9, 2019, 7:25pm UTC](https://forum.openwrt.org/t/custom-channel-bandwidth/28255/6 "2019-01-09T19:25:31Z")
Honestly, I think the 3-40MHz does refer to Wi-Fi. Furthermore, Doodle claims to be able to adjust the guard interval lengh as well, suitable for bigger coverage areas. Anyway, I found this hack, which allows changing the BW by reducing the chipset clock speed: > **[Underclocking the ESP8266 Leads To WiFi Weirdness](https://hackaday.com/2019/01/04/underclocking-the-esp8266-leads-to-wifi-weirdness/)** > > Sometimes the best hacks come from the most basic of questions. In this case, \[CNLohr\] was wondering what would happen if he started to reduce the clock speed of the ESP8266’s Baseband PLL (B… ---
**Author:** ![Pippo](https://forum.openwrt.org/letter_avatar/pippo/32/5_5575768a8748004e209b776fc1b2916d.png) [@Pippo](https://forum.openwrt.org/u/Pippo)\ **Post date:** [January 10, 2019, 8:39am UTC](https://forum.openwrt.org/t/custom-channel-bandwidth/28255/7 "2019-01-10T08:39:25Z")
Is the data link used only for miitary UAV or like satellite phone is available to commercial private people ? Is it expensive ? > **[Mini Micro Data Link System (M2DLS) - Commtact](https://commtact.co.il/products/micro-data-link-system/)** > > M2DLS Mini Micro Data Link System MINI UAS VTOL UAS LOITERING MUNITION UGV Download Brochure Download Brochure The Mini Micro Data Link System (M2DLS) is an advanced single unit digital data link system specifically designed for micro and small size...