Smoother Frequency Tracking with Icom Transceivers

Icom transceivers can be configured to automatically report frequency and mode changes via the CI-V bus, but tracking changes to other status made accessible by the transceiver -- e.g. RX filter width, RX/TX state, split state, passband tuning, S-meter reading -- requires Commander to continuously issue directives commanding the transceiver to report those additional elements of its status; this activity is referred to as polling the transceiver. Because CI-V Transceive, the transceiver's option to automatically report frequency and mode changes, has when enabled produced unreliable operation, Commander has included report frequency and report mode directives in its polling sequence (the set of directives continuously sent to the transceiver in order to track its status), and users have been advised to disable their transceiver's CI-V Transceive option.

For example, here's Commander's polling sequence for the IC-7300:

Note that the report frequency directives are repeated, reducing the time between frequency updates and thus increasing the perceived smoothness of frequency tracking. The report S-meter and report mode directives are also repeated within the sequence, but less frequently. The report current VFO frequency directives are issued because external devices like tuners and amplifiers monitor their responses to track the transceiver's frequency; these devices may not monitor responses to the more recently-introduced report VFO A frequency and report VFO B frequency commands.

Continuous polling is controlled by Commander's Interrogation option; this should be enabled for all typical usage scenarios.

The rate at which directives are conveyed to the transceiver and the rate at which responses are returned to your computer is governed by the CI-V bus baud rate, an option controlled by a transceiver menu setting; increasing the CI-V bus baud rate will improve the smoothness of frequency tracking - so the fastest available baud rate should be selected. Recent Icom transceivers provide the option of using a USB port connected to your computer to create a virtual COM port for the CI-V bus; if the transceiver's CI-V USB Port menu option is set to Unlink from [REMOTE], a maximum baud rate of 115,200 will be available. The Baud selector in the Primary CAT Serial Port panel on Commander's Configuration window's Ports tab should specify the CI-V bus baud rate for which the transceiver is configured.

Command Interval

The Command Interval setting controls how rapidly Commander issues polling sequence and other directives: reducing the specified interval results in more frequent reports, which yields smoother tracking.

If Commander issues a directive that is expected prompt a response from the transceiver -- like report split or report VFO A frequency -- it will not issue another directive until that response has been received or a timeout expires. However, older Icom radios like the IC-706 or IC-735 cannot handle incoming directives at the maximum sequential rate. Start with a Command Interval of 200 ms, and then gradually reduce it until erratic frequency reporting is noted; then increase the Command Interval by 50%.

Enabling CI-V Transceive

All Icom transceivers have a CI-V transceive menu option that, when enabled, causes the transceiver to automatically report frequency and mode changes. Originally introduced so a separate receiver and transmitter could function as a transceiver, enabling the CI-V transceive option produces very smooth frequency change tracking. However, the frequency and mode reports automatically generated by the transceiver can collide on the CI-V bus with directives issued by Commander. Enabling Commander's Verify CI-V command acceptance option should have automatically recovered from any collision damage caused by the transceiver's CI-V transceive menu option being enabled, but enabling CI-V transceive remained inexplicably problematic; thus Commander's configuration instructions have long recommended that the transceiver's CI-V transceive menu option be kept disabled.

Icom's introduction of the IC-7300, IC-7610, IC-7850, and IC-7851 with the ability to report spectrum scope data via the CI-V bus led to Commander's extension to display a Spectrum-Waterfall window. The new Spectrum-Waterfall window increased the demand for smooth frequency tracking, prompting another effort at making it possible to enable the transceiver's CI-V transceive menu setting. This effort identified the undocumented transceiver behavior responsible for the problematic behavior. Commander 13.7.0 has been extended to prevent these adverse behaviors; thus when controlling an Icom transceiver while using Commander 13.7.0 or later, the transceiver's CI-V transceive menu setting can be enabled if Commander's Verify CI-V command acceptance option is also enabled. Commander's Interrogation option should be enabled and its Command Interval option should be set to 100 ms. (200 ms. for older Icom transceivers like the IC-706 or IC-735) so that the other status items are also tracked.

If the red CI-V indicator appears the right of the Scan box on Commander's Main window, the transceiver has detected and reported a CI-V bus collision; increase the Command Interval by 50% and, clear the CI-V indicator by clicking it.

The IC-7300, IC-7610, IC-7850, and IC-7851 accept CI-V commands that enable or disable their CI-V Transceive options; you can use these in an initial command sequence to enable CI-V Transceive after running an application that disables it:

Controlling Multiple Transceivers

If you have Commander configured to control more than one transceiver, enable Interrogate, specify the Command Interval, and set the CI-V bus Baud rate on the Configuration window's MultiRadio tab.

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IcomCIVTransceive (last edited 2018-07-30 20:59:42 by AA6YQ)