Return-Path: Message-ID: <4489519A.9080200@csr.com> Date: Fri, 09 Jun 2006 11:46:50 +0100 From: Steven Singer MIME-Version: 1.0 To: BlueZ users References: <20060608231759.M13160@cos.ufrj.br> In-Reply-To: <20060608231759.M13160@cos.ufrj.br> Subject: Re: [Bluez-users] Min. output power of TPL Reply-To: BlueZ users List-Id: BlueZ users List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Sender: bluez-users-bounces@lists.sourceforge.net Errors-To: bluez-users-bounces@lists.sourceforge.net Alexandre Coser Monteiro wrote: > Anyone can explain to me, how its possible to read in Trasmit Power Level command > by hcitool a valou of -20 dBm, if in power class definition of bluetooth its defined > that the Minimum Output Power for Class 1 device is 0dBm !?! Is it my device broken ? 0 dBm is the minimum maximum power. That is a device must be able to reach at least 0 dBm to be able to call itself class 1. What you're reading is the current output power. Devices are allowed to power control below 0 dBm if they don't need the extra power. This reduces the interference on neighbouring networks. There is an option in the HCI command to read the maximum transmit power that will be used. The relevant section of the spec is, in the BT 2.0 spec, volume 2, part A, section 3, table 3.1 (particularly the footnotes) on page 31: Maximum Output Nominal Minimum Power Power Output Output Power Class (Pmax) Power Power [1] Control 1 100 mW (20 dBm) N/A 1 mW (0 dBm) Pmin<+4 dBm to Pmax Optional: Pmin [2] to Pmax [...] [1] Minimum output power at maximum power setting. [2] The lower power limit Pmin<-30dBm is suggested but is not mandatory, and may be chosen according to application needs. Note also, that class 1 devices must limit themselves to class 2 maximum power (+4 dBm) if the remote side does not support the signalling required to control its peer's output power (same page of the spec). - Steven -- To access the latest news from CSR copy this link into a web browser: http://www.csr.com/email_sig.php _______________________________________________ Bluez-users mailing list Bluez-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bluez-users