BT 4.0 (Bluetooth Low Energy) 是定频还是跳频呢？

BLUETOOTH SPECIFICATION Version 4.0 [Vol 1]

BLE

In the LE core system

3.3.2 LE Physical Channels
In the LE core system, two Bluetooth devices use a shared physical channel
for communication. To achieve this, their transceivers need to be tuned to the
same PHY frequency at the same time, and they need to be within a nominal
range of each other.
Given that the number of PHY channels is limited, and many Bluetooth devices
can be operating independently within the same spatial and temporal area,
there is a strong likelihood of two pairs of independent Bluetooth devices having
their transceivers tuned to the same PHY channel, resulting in a physical
channel collision. Unlike BR/EDR where an access code is used to identify the
piconet, LE uses a randomly generated Access Address to identify a physical
link between devices. In the event that two devices happen to share the same
PHY channel in the same area, the targeted device Access Address is used as
a correlator to determine to which device the communication is directed.
Two LE physical channels are defined. Each is optimized and used for a different
purpose. The LE piconet channel is used for communication between connected
devices and is associated with a specific piconet. The LE advertisement
broadcast channel is used for broadcasting advertisements to LE devices.
These advertisements can be used to discover, connect or send user data to
scanner or initiator devices.
An LE device can only use one of these LE physical channels at any given
time. In order to support multiple concurrent operations the device uses timedivision
multiplexing between the channels. In this way a Bluetooth device can
appear to support connected devices while simultaneously sending advertising
broadcasts.

1.4 PHYSICAL CHANNEL
As specified in Part A, Section 2, 40 RF Channels are defined in the 2.4GHz
ISM band. These RF Channels are allocated into two LE physical channels:
advertising and data. The advertising physical channel uses three RF channels
for discovering devices, initiating a connection and broadcasting data. The data
physical channel uses up to 37 (see Section 4.5.8) RF channels for communication
between connected devices. Each of these RF Channels is allocated a
unique channel index (see Section 1.4.1).

Two devices that wish to communicate use a shared physical channel. To
achieve this, their transceivers must be tuned to the same RF Channel at the
same time.

Given that the number of RF Channels is limited, and that many Bluetooth
devices may be operating independently within the same spatial and temporal
area, there is a strong likelihood of two independent Bluetooth devices having
their transceivers tuned to the same RF Channel, resulting in a physical channel
collision. To mitigate the unwanted effects of this collision, each transmission
on a physical channel starts with an Access Address that is used as a
correlation code by devices tuned to the physical channel. This Access
Address is a property of the physical channel. The Access Address is present
at the start of every transmitted packet.
The Link Layer uses one physical channel at a given time.
Whenever the Link Layer is synchronized to the timing, frequency and Access
Address of a physical channel it is said to be 'connected' to this channel
(whether or not it is actively involved in communications over the channel).

是跳频，我们在频谱仪上看了

Helen.ma 发表于 2014-11-19 20:10
是跳频，我们在频谱仪上看了

BLE 4.0是跳频？理论上BLE模式就是定频的，类似wifi。
现在有很多模块是双模所以，会有类似普通2.1 3.0蓝牙的跳频，但是如果有蓝牙4.0的BLE功能，那么应该就是定频的了。

Helen 真有专业精神！