Cardpod Overview

Cardpodcaster

This is a typical Cardpodcaster or Cardpod Recorder. Unfortunately we have not yet inspected an actual instance or found suppliers of other similar models that include voice record capability, despite the fact that System on Chips for Cardpods include voice record capability. Optidonal hardware features that could be considered when selecting actual models are discussed below. Firmware features will be discussed separately and should not affect initial procurement as long as the capability to develop and install modified firmware is ensured by negotiation with manufacturer of the model(s) selected.

Taibotech RWM008

Taibotech model RWM008 Cardpodcaster.

http://www.taibotech.com/Products/RWM008_2.htm

It is advertized here at USD $11.25 (quantity 1). Not seen.

Cardpod Player

 A number of player only models (with no voice record capability) are available, both with and without FM radio receivers. These are only marginally cheaper so should only be considered if recorder supplies unavailable for urgent deployment in first batch. As long as the large majority of Cardpods eventually deployed include record capability, those initially deployed that are play only would still remain useful (eg with portable loudspeakers), relying on recorders also being deployed in the same places when recording is required.

Radio Broadcast Receiver

Many MP3 player and especially recorder models include separate chips for FM receivers, using the earset cable as antenna. Reception quality may be poor but could perhaps be improved by careful design of the earset and antenna. Additional manufacturing cost is very small so may be worth including even if not especially useful. Similar separate chips are also available for AM receivers and combined AM/FM receivers but models including them seem to be less common, perhaps because they require external antenna. AM radio has much wider coverage areas so should be carefully considered. Cheap receivers for digital radio broadcasts do not yet seem to be available but could be very useful for recording to flash cards. In practice it is probably better for broadcasts (including digital broadcasts) to be recorded (and compressed) using USB receiver attached to a school XO that provides DTN podcast relay services for the Cardpod users. This would also include RTC for unattended recording (see below) and would be easier to setup with good antenna for high quality reception. Nevertheless casual personal broadcast reception using the same portable device and earset, could be well worth the very small additional cost. FM broadcasts include a data channel for track identification and such services as weather and highway traffic information for travellers with car FM radios. The standard chipsets provide access to this data and it might be possible to use it for some sort of paging mechanism via suitably equipped local community radio stations.

Real Time Clock

A logical complement to a recorder with radio broadcast receiver is a Real Time Clock (RTC) facility so that scheduled recordings can be made from broadcasts unattended. There are MP3 clock radios available but these include loudspeakers and appear to be primarily intended for domestic use with grid power. A suitable SoC, which also includes audio compression to MP3 or FLAC is also available but we have not yet identified any cheap models using that SoC with card reader. This chipset also includes USB On The Go so models based on it will probably be most suitable even if slightly more expensive. Without audio compression an RTC adds little since the recording would need to be compressed to avoid using excessive space on flash cards and the XO used for compression could be setup to do any unattended broadcast recording required. When a chipset with RTC and compression is available the device can also be used as a fancy alarm watch and can maintain proper timestamps on recorded notes. However care should be taken that the sleep mode maintaining current time uses absolutely minimal power. Otherwise it would be necessary to turn the device off completely (eg by removing battery at the end of a day's use) and therefore necessary to reset the clock when turning it back on each day.

Inputs

A microphone input or line input connector could be useful for higher quality recordings using a more expensive external microphone. However the additional cost may not be justified - especially if the same result can be achieved by using a USB microphone attached to a USB OTG port or if the additional features in professional quality digital audio recorders are needed for broadcast quality anyway.

Outputs

The standard 3.5mm 32 Ohm stereo audio jack for earphones or portable loudspeakers seems adequate. Models with built-in loudspeakers merely reduce flexibility. Separate portable loudspeakers with their own amplifiers and batteries woould be better and can be procured entirely independently of the selecting of the Cardpod device itself.

The retail packaging with  earbuds does not seem to add much value when the supply is for government distribution rather than display on retail channels. Batteries and flash cards (pre-loaded with initial content) have to be supplied through the same channels anyway so any packaging and selection of earbuds could be organized separately. Earbuds supplied by device manufacturer are likely to be of poor quality with poor FM reception when using their antennas as cables. But such supply may be the cheapest option. Canal earphones (with soft rubber caps that seal them to the ear canal) provide higher quality and result in lower volumes (with less battery usage). These may however be significantly more expensive. Earsets must not be shared and will be lost or damaged, so ongoing separate supply arrangements will be necessary anyway.

A well desiged earphone cable can also provide for attachment to the lanyard ring on a Cardpod device so as to act as a lanyard (eg with a loop around the neck, which should be breakable to avoid damage in case of being wrenched by a thief).

If a four connector 3.5mm output jack is used instead of the standard 3 connector stereo jack, it should still be possible to use standard earsets etc but also possible to use those with a special single button "clicker" control on the earset cable. There should be little extra manufacturing cost for models that include the necessary internal connection so that the Cardpod device can be left in a pocket with only the clicker button used to control it. eg single isolated click to toggle pause/play, double click to skip to next track, triple click to rewind to previous track.

USB OTG

USB "On The Go" is an important new standard which does not seem to implemented in cheaper models although the additional manufacturing cost of using the required standard microAB USB connector should be negligible and at least one SoC is already available that supports USB OTG. The main benefit is that this is the standard used to copy data between two cell phones and to supply power to cell phones from USB battery charger devices. With appropriate firmware it should be possible to copy files between two Cardpods (including synchronization) without needing an XO and between a Cardpod and a cell phone.

Other possible applications include USB microphones, external keyboard and audio output.

Controls

Additional buttons beyond the standard 5 make it significantly easier to learn additional functions such as A-B repeat and split recording and to navigate through menus for special firmware features etc. However they also add to the cost and it should always be possible for firmware to implement the same features using more complex (harder to learn) sequences with the standard 5 buttons.

A separate off switch can be helpful for eliminating all battery drain when not in use, but the same result can be achieved by removing the battery.

A separate "hold" slide can be helpful for preventing accidental button presses that start or stop recording or playback etc, but this can be avoided by taking care.

Display

Larger and higher quality displays are widely available and do make it much easier to learn how special features work as well as enabling text readers that could store large amounts of information for reading. The most popular MP3 players in developed countries are able to play movies on their high quality (but still very small) colour screens. These are significantly more expensive and the extra cost of minor improvements to the display just for easier use of audio is probably not worthwhile given the tiny screen size unsuitable for reading anyway. Careful evaluation should be made of the possible benefits from reading text, bearing in mind the major increase in battery consumption and alternatives from print, TV computers or a full XO Laptop with much more usable screen when seriously using text and pictures instead of just audio. Minimal lookup of text information is still feasible with the cheapest displays.