diff options
Diffstat (limited to 'host/docs/vrt_chdr.dox')
| -rw-r--r-- | host/docs/vrt_chdr.dox | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/host/docs/vrt_chdr.dox b/host/docs/vrt_chdr.dox index 560f0b6a3..a2d36c93e 100644 --- a/host/docs/vrt_chdr.dox +++ b/host/docs/vrt_chdr.dox @@ -7,8 +7,8 @@ If one were to sniff Ethernet traffic between a USRP and a PC, the packets would radio transport protocol. For USRP devices, two radio transport protocols are relevant: VRT (the VITA Radio Transport protocol) -and CVITA (compressed VITA), also known as CHDR. Generation-3 devices and the B200 use CHDR, the rest -use VRT. +and CHDR (compressed header, an Ettus-specific protocol). +Generation-3 devices and the B200 use CHDR, the rest use VRT. \section rtp_vrt VRT @@ -19,13 +19,12 @@ VRT is a very verbose standard, and only a subset is implemented in UHD/USRPs. The full standard is available from the VITA website: http://www.vita.com . -\section rtp_chdr CVITA (CHDR) +\section rtp_chdr CHDR For the third generation of Ettus devices, a new type transport protocol was designed. It reduces the complexity of the original standard and uses a fixed-length 64-Bit header -for everything except the timestamp. Because this is a "compressed" form of VITA, it -was dubbed "Compressed VITA" (CVITA). The compressed header is called CHDR, which is why -the protocol is often called CHDR itself (pronounced like the cheese "cheddar"). +for everything except the timestamp. Because it is "compressed" into a 64-bit heaer, it +was dubbed CHDR (pronounced like the cheese "cheddar"). By compressing all information into a 64-bit line, the header can efficiently be parsed in newer FPGAs, where the common streaming protocol is 64-Bit AXI. The first line in a @@ -33,7 +32,7 @@ packet already provides all necessary information to proceed. Some CHDR-specific functions can be found in: uhd::transport::vrt::chdr. -The form of a CVITA packet is the following: +The form of a CHDR packet is the following: Address (Bytes) | Length (Bytes) | Payload ----------------|----------------|---------------------------- @@ -76,7 +75,7 @@ for Ethernet links as well as USB (e.g., for the B210). Relevant code sections for the radio transport layer are: * uhd::transport::vrt - Namespace for radio transport protocol related functions and definitions -* uhd::transport::vrt::chdr - Sub-namespace specifically for CVITA/CHDR +* uhd::transport::vrt::chdr - Sub-namespace specifically for CHDR * uhd::sid_t - Datatype to represent SIDs */ |