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--- en:users:drivers:zd1211rw:rftypes [2015/01/26 09:49]
+++ en:users:drivers:zd1211rw:rftypes [2015/01/26 09:49] (current)
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+==== RF Transceivers ====
+Each ZD1211-based WLAN adapter actually combines an RF transceiver chip with the ZD1211 (RF: //radio frequency//). The RF chip is basically a radio, responsible for transmitting data into the air at the specified frequency, and for listening for incoming data.
+The RF chip must be programmed from the device driver, and this task is complicated by the fact that different ZD1211-based products come with different RF chips.
+Some RF chips are better than others, some of them only work with 802.11b/g, others work with 802.11a/b/g.
+It appears that the USB ID does not determine RF type, as various devices have been spotted with the same IDs but different RFs.
+The AL2230 and RF2959 devices were common in earlier ZyDAS devices, with a few AL7230B devices appearing as well for 802.11a support. As of February 2007, the primary devices being produced now appear to be either AL2230S-based or UW2453-based.
+==== How do I find out which RF is present in my device? ====
+Using the zd1211rw driver:
+<code># dmesg | grep 'zd1211b\? chip'
+zd1211 chip 07b8:6001 v4330 full 00-12-0e RF2959_RF pa0 g----</code>
+In the above example, you can see that my RF is the RF2959.
+Please note that the AL2230 comes in 2 forms: AL2230 and AL2230S. With zd1211rw, the difference between the 2 is denoted by the 'S' flag at the end of the chip ID line. For example, the following device is AL2230S:
+<code>zd1211b chip 0ace:1215 v4810 high 00-02-72 AL2230_RF pa0 g--NS</code>
+This one is standard AL2230:
+<code>zd1211b chip 0ace:1215 v4810 high 00-02-72 AL2230_RF pa0 g--N-</code>
+If you are using the [[http://zd1211.ath.cx/download/|ZyDAS-based driver]], you can find out your RF type as follows:
+<code># dmesg | grep -A 1 "PA type" | tail --l 1
+AiroHa AL2230RF</code>
+The vendor driver explicitly detects AL2230 and AL2230S, so you do not have to worry about the difference there.
+If you have a RF which is not listed here, please report it to the mailing list.
+==== Known RF types ====
+=== Airoha AL2230 - 802.11b/g ===
+The [[http://www.airoha.com.tw/AL2230.htm|AL2230]] appears to be fairly decent in terms of signal reception without any external antenna. Airoha publish a [[http://www.airoha.com.tw/pdf/AL2230S.pdf|datasheet]] about the chip, but the public version does not include technical details.
+We have tried contacting Airoha for more detailed technical documentation, however they became unresponsive after they realised that we are not a huge corporation wanting to buy thousands of their devices...
+=== Airoha AL7230B - 802.11a/b/g ===
+The [[http://www.airoha.com.tw/AL7230.htm|AL7230B]] ([[http://www.airoha.com.tw/pdf/AL7230.pdf|datasheet]]) is probably just an extended version of the AL2230 which supports 802.11a. Interestingly, the first sighting of this RF (in a Trendnet device) is only advertised as b/g compatible. Someone should check and see if RF type is really the only factor that decides whether a device supports 802.11a.
+=== RFMD RF2959 - 802.11b/g ===
+We suspect the RF2959 is one of the cheaper RF transceivers available on the market, however it appears to work relatively well.
+RFMD were kind enough to provide us with technical documentation about these devices, under non-distributive terms.
+=== Ubec UW2453 - 802.11b/g ===
+The [[http://www.ubec.com.tw/product/uw2543.html|UW2453 RF]] started appearing in devices in 2007. At least to someone with limited understanding of RF chips, this appears to be similar to the other available RF's. Ubec publish [[http://www.ubec.com.tw/product/downfiles/uw2453/DS-2453-01%20v1%200.pdf|full technical specifications]] for this chip.
+UW2453 support will be added to zd1211rw as of Linux 2.6.23.
+=== Airoha AL2230S - 802.11b/g ===
+The [[http://www.airoha.com/AL2230.htm|AL2230S]] appears to be the next generation version of the earlier AL2230. The exact differences are unclear. This RF started appearing in ZD1211 devices in 2007.
+AL2230S support will be added to zd1211rw as of Linux 2.6.22.

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