CSR藍牙固件關于對信號強度RSSI的應用HCI Implementation (bcore-an-032Pa).doc

6.51 (HCI: 7.5.3) Read_Link_Quality6.51（HCI：7.5.3）Read_Link_QualityThis command obtains a value in the range 0 to 0xff, describing the quality of an ACL connection.此命令獲得一個說明ACL連接質量的值，其介于0至0xff之間。The values meaning is manufacturer-specific.這個值的意思是制造商特定的。The value is derived from an averaged bit error rate (BER) measurement, updated as packets are received.該值是源于平均誤碼率（BER）的測量，接收數(shù)據(jù)包時更新。The BER value is derived from parts of radio packets that support FEC error correction:誤碼率是來自部分無線數(shù)據(jù)包，支持FEC的錯誤： All packets headers 所有數(shù)據(jù)包的包頭 The payloads of DM1, DM3, DM5, HV1 and HV2 packetsDM1，DM3，DM5，HV1和HV2包的有效載荷 The data parts of DV packetsDV包的數(shù)據(jù)部分The technique used to derive BER values is not precise; it is intended only to give an indication of link quality rather than act as a precise, calibrated instrument.該手法用于計算誤碼率的值是不準確的，它只是為了指示鏈路的質量，而不是作為一個精確的測量指示。Links BER values are used internally to adapt to changes in link quality, notably to support CQDDR (Channel Quality Driven Data Rate).鏈路的誤碼率值是在內部使用，以適應變化的高質量鏈接，特別是支持CQDDR（根據(jù)信道質量確定數(shù)據(jù)速率）。The HCI commands values are as follows.HCI命令的值如下。 Between 0xff and 0xd7 each bit distance represents 0.0025% BER. Thus: 在0xff和0xd7間的每個位代表0.0025的誤碼率。因此： Between 0xd6 and 0x5a each bit distance represents 0.08% BER. Thus:在0xd6和0x5a間的每個位代表誤碼率0.08。因此： Between 0x59 and 0x00 each bit distance represents 0.64% BER.在0x59和0x00間的每個位代表誤碼率0.64。As a rule of thumb, a link with a BER between 0 and 0.1% is workable. 根據(jù)經(jīng)驗，鏈路的誤碼率在0和0.1%之間是可行的。Trying to run a link with a BER above 1% gives poor results. 嘗試運行一個誤碼率大于1%的連接會給出差的結果。Note: 注意：For EDR links these tables are not valid. It is not possible to convert link quality into BER.這些表對于EDR鏈路無效。它不可能轉化為鏈路質量的誤碼率。6.52 (HCI: 7.5.4) Read_RSSI 6.52（HCI：7.5.4）Read_RSSI A common user hope is to use this commands return values as the basis of a general-purpose signal strength meter. 通常用戶希望使用此命令返回基于多方信號強度計量的值。Unfortunately, the command, as specified by BT1.1, is almost useless for this role. 不幸的是，這個命令，由BT1.1指定，這個角色幾乎是無用的。 While a links received signal strength is within the Golden Receive Power Range the command returns an RSSI value of zero. 在鏈路處于黃金接收功率范圍內時，此命令返回一個零的RSSI值。 The Golden Receive Power Range is normally around 20dBm wide, crudely equating to a physical range factor of ten. (For example, between 1m and 10m the RSSI value could be zero.)黃金接收功率范圍是通常在20dBm寬度周圍，粗略的等同于10的物理范圍。（例如，1米和10米之間的RSSI的值都可以是零。） The RSSI value only goes positive or negative when the received signal slips outside the Golden Range. RSSI的值僅僅是變正或負，當收到的信號在黃金范圍外時。 Where dynamic power control is available, the firmwares LM emits LMP_incr_power_req or LMP_decr_power_req messages to the Bluetooth peer to try to bring the received signal strength back into the Golden Range. 當動態(tài)功率控制是可用的，固件的LM發(fā)出LMP_incr_power_req或LMP_decr_power_req消息給藍牙匹配嘗試把接收到的信號強度調回黃金范圍。BT1.1 requires only that the function return a negative value when the RSSI is below the Golden Range, zero within it, and a positive value when the RSSI is above the Golden Range. BT1.1只要求函數(shù)在低于黃金范圍時返回一個負的RSSI，零也在其中，高于黃金范圍時返回一個正的RSSI。 When the RSSI is above the Golden Range, the firmware returns a positive number. 當RSSI高于黃金范圍時，固件返回一個正數(shù)。 The value is an approximation of the dB between the top of the Golden Range and the RSSI. 該值是一個近似的dB，在黃金范圍的頂部和RSSI之間。The value is very crude: it can be 5dB from the real value, there is no guarantee that a constant RSSI will give a constant return value, and thus there is no guarantee that the mapping from RSSI to the returned value will be monotonic. 該值是很簡陋：它可以與真實的值相差5dB，但不能保證一個恒定不變的RSSI將返回一個恒定不變的值，所以是不能保證從RSSI的映射到返回的值將是單調的。 When the RSSI is within the Golden Range, the firmware returns zero. 當 RSSI在黃金范圍內時，固件返回零。 When the RSSI is below the Golden Range, the firmware returns a negative number. 當RSSI低于黃金范圍時，固件返回一個負數(shù)。 The value is an approximation of the dB between the RSSI and the bottom of the Golden Range. 該值是一個近似的dB，在黃金范圍的底部和RSSI之間。The value is even more crude than for positive values: it can be more than 5dB from the real value, there is no guarantee that a constant RSSI will give a constant return value, thus there is no guarantee that the mapping from RSSI to the returned value will be monotonic, and the value clips at a minimum of approximately -10dB. 該值甚至比正值更粗糙：它可以與真實的值差5dB，但不能保證一個恒定不變的RSSI將返回一個恒定不變的值，因此也不能保證，從返回的映射的RSSI值將是單調的，并在約- 10dB的最低值剪輯。 The firmware therefore supports the bare minimum required by BT1.1. 因此，該固件支持的最低限度為BT1.1。 This is not useful for a general-purpose power meter. 這不是一個有用的通用功率計。 Behaviour for HCIStack1.2v19.2 and Later Builds HCIStack1.2v19.2及其后續(xù)構建的行為On HCIStack1.2v19.2 and later builds the accuracy of the value returned by HCI_Read_RSSI has been improved. 在HCIStack1.2v19.2及其以后構建的程序中，HCI_Read_RSSI的返回值準確性已有所改善。 In addition, reading BCCMD command RSSI_ACL retrieves an indication of the RSSI for the given ACL handle (rather than how far above or below the golden range the RSSI is, as HCI_Read_RSSI does). 此外，閱讀BCCMD命令RSSI_ACL為給定的ACL檢索RSSI的指示（而不是遠遠高于或低于RRSI的黃金范圍，正如HCI_Read_RSSI一樣）。The value returned should be interpreted as a signed twos-complement (16 bit) integer. The value returned is always negative because the reading saturates at about -20 dBm.返回值應解釋為一個有符號整數(shù)的補碼（16位）。返回值始終是負的，因為閱讀的飽和約-20dBm。BCCMD RSSI_ACL returns OK if a signal strength can be supplied, and ERROR if the handle is no longer valid. 如果信號強度可以提供，那么BCCMD RSSI_ACL返回正確，否則返回錯誤句柄不再正確。 The signal strength returned is zero when the chip returns the ERROR status. The value returned is a rolling average and responds more slowly to changes when the data is transmitted less frequently. 當芯片返回的狀態(tài)為錯誤時，RSSI返回值為0。該值返回是平均滾動的，在數(shù)據(jù)傳輸不頻繁的時候，其改變的也慢。 Note: 注意：The accuracy of the result is likely to be within +/- 4dBm. 結果準確性的可能是在+ / - 4dBm。However, this measurement is not calibrated or tested on a per-chip basis and CSR makes no warranty about its accuracy.然而，RSSI的測量不是校驗或測試每個芯片的基準，CSR對其準確性不作任何保證。Users should establish for themselves whether this meets their requirements across a range of devices. 用戶應自己建立能滿足其需求的命令。6.37 (HCI: 7.3.37) Read_Transmit_Power_LevelWhen used to o