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Planetary Communications in Traveller

This article originally appeared in the January/February 2022 issue.

They are there on page 13 of Classic Traveller Book 3: Worlds and Adventures (and page 47 of Cepheus Engine), the Short Range Communicator (Cr100, 10km), Medium Range Communicator (Cr200, 30km) and the Long Range Communicator (Cr500, 500km and ships in orbit). As even a teenager with an interest in radio comms this grated, and 40 years later with radio communications having taken up and important part of my career it still annoys! Mongoose Traveller improved things slightly – their Comm is very much a mobile/smart phone, but their Transceiver still assumes that range is dependent on TL (first edition) or size (both editions).

Yes, this is going to be a “How Traveller Got My Real-World Career Wrong And Now I’m Going To Fix It” article, but hopefully it will be relatively short, playable, and add some ideas for colour in your Traveller games.

First, I’ll look at “everyday” communications, and then at “expeditionary” communications.

Note: All tasks are given using Mongoose Traveller second edition definitions but should be readily convertible to other Traveller editions. Tasks are Comms/EDU unless otherwise specified.

Everyday Communications

Table 1 presents a tech-level by tech-level guide to the dominant communications system on a planet, and Table 2 (at the end) details the equipment that the Travellers might need. The paragraphs below provide more detail on each technology stage.

TL0/1/2 – Couriers: At the lowest tech levels communications is by simple courier, initially on foot and then later mounted, such as the mis-identified Poni of IISS logo fame. As societies develop a formal system of routes and post-houses is likely to develop, providing fresh mounts at regular intervals. Some form of paid service based on “stamps” might also develop. In these low-tech worlds the post-houses will, probably with hi-tech gear hidden, be useful places to find out what is going on in a region, and maybe even pick up the odd low-tech ticket.

TL1/2/3 – Semaphore: The earliest technological solution to communications is likely to be some form of semaphore. At its simplest this could be a fire beacon used to generate smoke signals, then polished metals or mirrors, but a more “professional” system is likely to involve some form of mechanical apparatus visible at a great distance – such as moving arms or moving balls. The maintenance and operation of these systems would be a skilled profession, such as some form of guild with its own traditions and secrets. For a great exploration of such a system and guild read the short story “The Signaller” by Keith Roberts in his counter-factual (verging on steampunk) Pavane novel. In times of strife there may be low-tech mercenary tickets going to protect (or attack) such signalling towers, and maybe even higher tech tickets if the opposition has invested in off-world support. A variation on the semaphore model could be something more like maritime signalling flags, particularly if suspended from high-flying kits or balloons.

TL3 – Wired Telegraph: With the advent of electricity, wired telegraphy becomes possible with some form of transmitting and receiving equipment at either end, and some form of encode/decode system (manual or automatic). Telegraph operators will be very popular and knowledgeable about their localities and a great source of information. Jobs might be available investigating breaks in the line, especially where remote relays have been established; the PCs had best beware of walking into an ambush.

TL4 – Wireless Telegraph (WT): The invention of radio allows much of the infrastructure of wired telegraphy to be bypassed, and communications more easily established to outlying islands which may have needed submarine cables or even semaphore relays. WT is still a specialist skill and the message office still the font of all knowledge. The WT stations could even be called upon by Travellers with HF radios in their expeditionary gear if they get stuck in a remote location. Even more than with wired telegraphy the WT stations become of vital importance during any periods of unrest and protecting (or seizing) them would be high on a faction’s priorities and a good tasking for off-world mercenaries.

TL5/6 – Voice Telephony: Voice telephony begins to democratise the real-time communications service. Early systems use manual switchboards whose operators probably exceed even telegraph operators as local know-all’s. Electro-mechanical switches then take over, followed by digital switches. Travellers with Comms 3+ might be able to start hacking the system (phone-phreaking, anyone?), and, with a suitably ancient modem, use it for data communications. City exchanges are again important key infrastructure to be seized or defended in times of unrest.

TL7/8 – Global Telephony: Fairly rapidly local and national telecoms networks will be joined by point-to-point microwave links and submarine cables, creating a global telephony network. The use of modems over the network for low speed data will become common place, soon to be supplemented and the replaced by dedicated data networks – the equivalent of the Internet. International and intercontinental calling will be expensive and possibly unreliable. A team that could bring in an ad-hoc global communications network might really help a faction seize power by being one step ahead of its rivals.

TL7/8+ Mobile Telephony and Mobile Data: The advent of mobile phone networks brings about the emergence of what Solomani techs refer to as the Negroponte switch. At earlier tech levels local line connected to long distance radio links, whereas now most calls (voice or data) are carried over local radio to long distance wire (or more likely fibre optic). For any net-runners on the team this opens up a whole new raft of hacking opportunities. Of more immediate benefit is that the PCs can roam onto local networks with their standard communicators (assume kit operates on networks up to 2 TL down), or readily buy a local device and airtime/data package at a ship or dispenser on arrival at the Downport. The Downport might also offer a relay service through to their ship (in High or Downport), enabling the PCs to “dial-home” from anywhere on the local system.

TL8/9+ - Satellite Communications: As rocketry becomes available an early use will be to deploy low orbit and then geostationary orbit communications satellites. These will make global telecoms cheaper and accessible to all. As well as boosting global connectivity they will also provide personal satcom capability to (the richer) individual users through satellite phones and modems. The shift from geostationary back to low orbit constellations will reduce power requirements (and hence size, cost, and operating time) making such communications even more ubiquitous and getting into otherwise out of the way places. Another option are satellites in highly elliptical Molniya orbits which provide long dwell times over areas of intended use.

Low population or lower tech worlds which are an established part of the Imperium may have a low capacity satcom network based on Geostationary or sparse Low Orbit constellations, run on a service contract by a local subsector/sector operator, megacorporation or even the IISS. On a balkanised world there may be some resistance to Low Orbit systems, each polity claiming a segment of the geostationary orbit.

Whilst satcom ground stations decrease in importance as their numbers multiply the satellite assets themselves become quite key, and there may be some interesting adventure opportunities in checking out satellites that have gone quiet, or in taking out constellations in the most effective manner.

Mongoose Traveller (both editions) talks about laser-transceivers, but apart from fixed-point to fixed-point via satellites or at very close range with line of sight (so typically < 10km) they are not going to be very useful as they need very precise alignment. However, they are often likely to be found in TL8+ inter-satellite links.

Exotic Modes

The description so far has assumed a fairly conventional technological progression, but this is a Science Fiction and alien universe, so some more exotic means might be available, particularly at the lower tech levels.

Sound Not Sight: Instead of visual semaphore a culture may make use of large sound horns. Whilst the use of horns and drums for tactical, short range, communication is quite common, their use over longer distances could also be a possibility. These may be huge drums or bells, possibly used with giant sound horns or sound mirrors in order to give the sound amplification and direction. Such a method is likely to be preferred on worlds with thicker atmospheres and possibly lighter winds, and/or where atmospheric traits limit optical visibility.

Creatures Not People: Even in some cultures and professions the use of homing birds has persisted in specific niches long after other technological means of communications have become commonplace. If the birds are smart (or trainable) enough they could provide such an efficient service that it actually delays the introduction of more technology-based solutions. The chances of this might be increased if birds with a good load capacity were available (parcel air mail!), where there is suspicion of technocrats, or where terrain made the laying of cable problematic (or the lack of – or excess of - an ionosphere made radio difficult. There could be a whole Guild associated with the training and management of the birds and the handling of the communications. And why limit a system to just using birds – wouldn’t Ponis be faster if they could be trained to deliver the mail without a human rider?

Pneumatic Tube Transport: Often appearing around TL3/4 Pneumatic Tube Transport works by placing a message (or object) in a cylindrical container which is then propelled along a message tube by compressed air or a partial vacuum. Whilst typically used for small packages and messages within a building or building complex, they have often been extended to whole city networks, and some cultures may develop larger scale systems, even to person size transport and continental scale networks. It may be possible that some variant becomes the “railway” of a culture, rather than the more familiar track and wheel model.

Biochemistry not Electronics: Whilst electricity and electronics has tended to guide the development of communications systems some environments and cultures might evolve a more biochemical model. Planet rhizomes or fungal mats could stretch for kilometres, perhaps 10s or 100s of kilometres and carry biochemical signals through the organisms. Primitive locals or highly advanced settlers might discover how to encode information onto these signals and then decode them elsewhere on the rhizome network (think Avatar’s Eywa and Tree of Souls for a more extreme version). A slightly less reliable but perhaps more long-distance communication could some through harnessing spores and finding some way to encode information in them.

Psionics: One step beyond the biochemical approach is a psionic one. At its most obvious this might mean a network of telepathic psions recruited to provide the communication service – which could range from simple message passing to complete immersive “mind-melds”. Obviously, such a system would be unpopular in Imperial space, but may be more acceptable elsewhere. In an emergent primitive psionic culture such a network might evolve naturally, the communication psions becoming honoured people like some form of priesthood or a powerful guild. Of course, it might not be the sentient race which has the psionic power, there may be animals or even “plants” which have the capability and which the sentients can harness (again like Eywa). The existence of a strong and capable telepathic system might severely restrict the driver for more technological solutions, and conflict between psions and “engineers” might be the result.

Table 1: Communications by Technology Level
TL0-2 Courier only. Using a fast animal assume 150 km/d. Using ships assume 300 km/d.
Ad-hoc use of semaphore in various forms (e.g. smoke).
TL3 Semaphore between major cities. Assume 1D×2hrs to send, and then a further 2D×2 hrs for reply (thinking time + transmission time!).
TL3 Wired telegraph between major cities, on same continent. Assume 1D hrs to send (there’s a queue), further 2D until a reply.
TL4 Wireless telegraph between major cities. Assume 1D×30 mins to send on same continent or one continent hop. Wired telegraph to major towns.
TL5 Voice telephony on same continent. Instant.

To make an intercontinental call. Average (8+). Try once per hour.

TL7/8 Global telephony from wired connection. Mobile telephony in all non-wilderness areas.

To make a mobile call from a rural area. Average (8+). Try once per hour.

To make a mobile call from a wilderness area. VDiff (12+). Try once per hour.

Satcom available with dedicated Satphones. See below for levels of service.

To make a satcom call. Difficult (10+). Try once per hour.

TL8/9+ Ubiquitous satellite-based comms. Available in 3 levels:
  1. Bare bones system deployable by a single large spaceship, e.g. to support exploration or military operations. May only cover part of the planet. (See below)

    To establish comms using a bare-bones system. Difficult (10+). Try once per hour.

  2. Permanent, low use basic system for a low pop world. Roll 2D6 under TL+2 for presence.

    To establish comms using a basic system. Routine (6+). Try once per hour.

  3. Permanent ubiquitous system. Nowhere is out of comms for anyone with a contemporary smartphone/communicator. Roll 2D6 under TL+4 for presence.

Interception of Communications

This article has been concerned with the everyday, legal uses of communications. Of course, there will always be those who wish to intercept a message in transit in order to exploit its contents, for political, military, economic, social or personal reasons. The first step in protecting against this is to use some form of code or cypher – and in fact the very first smoke or semaphore signals will perforce use some coding system. It won’t be long however before an arms race emerges between those trying to protect messages with ever more sophisticated coding systems – first manual then mechanical, electromechanical and eventually digital (or even quantum) – and those who are doing the best to break them – but perhaps that’s best left for another article!

Expeditionary Communications

Expeditionary communications is defined here as communications being provided without any reliance on local communications systems, and is also referred to as Portable Field Communications. Expeditionary communications are divided into short and long range, both emerge at TL5. If using local equipment add a +DM for each TL beyond this to a maximum of +4 for each of the tasks below.

Prior to TL5 and the invention of radio any “expeditionary” forces are likely to use variants of the available communications methods for more routine communications. Couriers would almost certainly be the mainstay, but rolling out a chain of semaphore stations, or even long telegraph cables, would be viable for large scale (i.e., colonisation or military) level expeditions.

Expeditionary Communications typically use two different groups of frequencies and equipment:

HF (High Frequency, also referred to as Short Wave, 3MHz – 30MHz), which is able to communicate across the globe by bouncing signals off the ionosphere. Note that if the planet does not have an ionosphere (typically Atmos 4 or less) then this mode does not work.

VHF (Very High Frequency, 30MHz – 300MHz) and UHF (Ultra High Frequency, 300MHz – 3 GHz) which typically communicate by line of sight only, and so often use elevated antennas to increase range. Not dependent on the ionosphere.

Whilst Very Low Frequency (VLF, 3-30kHz), Low Frequency (LF, 30kHz – 300kHz, also called Long Wave) and Medium Frequency (MF, 300kHz – 3 MHz, also called Medium Wave) bands can be used for communications their low frequency implies large wavelengths – which results in very large antennas (100m or even 1km plus!) and so they are far less suitable for expeditionary type work.

Frequencies above 3GHz are routinely used for communications to orbit (e.g. S and Ku bands), but they are very line of sight and easily absorbed and so have very short ranges (sometimes tens of metres) when used for ground communications.

Short Range Communications: Short Range Communications typically uses VHF or UHF, but HF may be used at the lowest TL. Range is largely dependent on terrain, range and power – see the equipment table.

To establish short range comms, Difficult (10+). Comms. Once per 10 mins.
DMs: -2 if urban or hilly, -4 if mountainous. Power DM from communicator class. -2 DM for each doubling of range beyond 5km. +1 DM vehicle, +2 DM fixed/mast, per end.

Long Range Communications: Long Range Communications typically uses HF. It can only be used if the planet has an ionosphere (take as Atmosphere > 4). Range is unlimited, but the equipment requires 1hr to set up. Skill is vital so double comms skill DM (i.e., a Level 1 Comms skills gives a +2 DM). It cannot be used for distances below 100km.

To establish long range comms, Formidable (14+). Double skill DM. Once per 10 mins.
DMs: Power DM from communicator class. Range DM as Range/1000km. +1 DM vehicle, +2 DM fixed, per end.

Satellite Communications: To support expeditions on the ground a common approach is to deploy a satellite train in low orbit, something like 10 to 20 satellites all chasing each other around on the same orbit so that one is always in sight, and in-orbit relays can then link back to the main ship. The satellites can cover a ground track about 100km wide, with additional bands being deployed for wider coverage. A single 10-20 satellite dispenser to cover one 100km planetary band is housed in a 4 dton (60m3) customised cargo pod, one standard shipping container. If the PCs are paying it costs Cr100k at TL9, reducing by 20% in cost, size and volume per TL. A fully equipped spaceship with 50 such containers can set up bare-bones global coverage in a week. Smaller worlds need less satellites, assume 6×Planetary Size containers.

Surface to Orbit

A ship in Low Orbit circles a Terran sized world about every 90 minutes, and is in range of a specific point on the surface for roughly 10% of the time (10 minutes). Almost any base station VHF/UHF communicator can be used to (Amateur Radio enthusiasts use just 25W on 144MHz to talk to the ISS – albeit with a decent antenna), but a dedicated Satphone or Satcom Communicator is a more reliable option – especially if there is an orbital satellite network to patch in to. Vehicle and even handheld communicators might be fine on small (Size 0-3) worlds. Orbit height increases visibility times, but so also does the need for a more powerful signal, so we’ve assumed they cancel out! Smaller worlds will provide longer coverage (assume 10%×8/Size).

To make a direct surface-to-orbit connection. Difficult (10+). Comms. Try once per hour. DM. -1 vehicle, -2 personal

Final Flourishes

If you want to add even more detail then you can also consider these extra rules and issues:

Table 2: Communications Equipment
Model TL Cost Range Pwr Mass Notes
Personal VHF/UHF Communicator 7 100Cr ~5km 5W 0.25kg  
The Icoh 734 is a general purpose hand-held radio used in a variety of roles from premises security and port operations to recreational boating, survey field trips and even criminals and terrorists. Rugged and water resistant to 2m it is a popular choice for outdoor activities. Comes with a 10cm helical rubber antenna and socket for an external antenna to double the range.
Model TL Cost Range Pwr Mass Notes
Vehicle VHF/UHF Communicator 6 300Cr ~10km 25W 5kg +1 Power DM
The Pyi 2502 is an early vehicle two-way radio, often found in law enforcement vehicles. Plentiful on the 2nd hand market they are also used by hobbyists. Channel selection is from a set of up to a dozen crystals – there is no free tuning. Radios with mismatched crystals will not be able to communicate – something that happens far more frequently than you’d hope!
Model TL Cost Range Pwr Mass Notes
Base VHF/UHF Communicator 6 1000Cr ~20km 50W 20kg Transportable
+2 Power DM
The Quadro Cityman is a solid piece of business equipment designed to meet the needs of the most demanding dispatcher in emergency service and transportation dispatch. Fully synthesiser driven it can operate on any frequency between 30MHz and 1.5GHz and supports a variety of modulation modes. Audio tone squelch removes background noise to support long duration use. An optional keypad enables text messaging support to radios using accepted signalling standards.
Model TL Cost Range Pwr Mass Notes
Manpack HF Communicator 7 1000Cr ~1000km 5W 10kg  
The ARC320 is a military grade manpack HF radio. Digitally controlled it can operate across the whole 3MHz-30MHz waveband in AM and SSB modes. A signalling key can be attached for low-bit rate (5bps) manual communications, and a data port can connect a computer for mid-bit rate (300bps) communications. The radio comes with a 1m whip antenna and an antenna pack to let you rig dipole antennas between trees or masts for long range communications. It should be noted that 30% of the weight is in batteries, and they will only last about an hour of transmit time, 12 hours of receive. Additional batteries weigh 3kg and cost 100Cr.
Model TL Cost Range Pwr Mass Notes
Vehicle HF Communicator 6 500Cr ~1000km 10W 6 +1 Power DM
The Taesu 353 is a popular ham radio HF transceiver designed to be highly portable. Often found in vehicles in large remote areas for mid-distance communication it is also often used by expeditions which can’t afford the mass or power requirements of a proper base transceiver. The Taesu line is regularly upgraded through TL6 and 7, making more use of digital displays, controls and memory. The latest version at high TL7, the 353n supports a number of esoteric modulation methods to optimise audio quality and data rates.
Model TL Cost Range Pwr Mass Notes
Base HF Communicator 7 2000Cr ~Global 100W 50 Transportable
+2 Power DM
The Kenbush TR1000 is a state of the art HF base radio. It features the latest software-define radio circuitry and adaptive HF techniques, “sensing” the conditions of the link and the ionosphere and adjusting power, modulation and processing to match. It is the radio to have if you and your team are heading out into the back of beyond.
Model TL Cost Range Pwr Mass Notes
Personal SatPhone 8 1000Cr n/a 2W 1  
The Osmium 3000 is the personal satphone for the traveller who doesn’t want to be tied to the cellular network. The blade antenna folds discretely into the body of the device when travelling, and dataports provide high bitrates for your computing devices when on the move. The 3000R, a ruggedised version which is fully waterproof is available for twice the price and mass.
Model TL Cost Range Pwr Mass Notes
Vehicle Satcom Terminal 8 3000Cr n/a 20W 10  
The Skywave is a small vehicle mounted satcom system which can be used either in the vehicle or dismounted. In the vehicle mode it has a low-profile “UFO on a stick” antenna mounted on the roof. This can be dismounted for static use or a 4 blade mini-parabolic used if the Skywave is converted to manpack mode. A local wireless hub is incorporated into the Skywave to provide data services to any nearby device.
Model TL Cost Range Pwr Mass Notes
Base Satcom Terminal 7 10000Cr n/a 60W 100 Transportable
Sitting at the top of the range is the Obara SatCom base station. The Obara is typically mounted inside a half-size container which is readily air or sea portable, and will fit on the back of a flat-bed or large pickup. In travel model the container includes the dish antenna, which includes 6 “petals” which are clipped together to make a 2m dish. A small generator is also included, but given the noise this is often supplemented by an external generator. In operational mode there is space in the container for one operator.
Model TL Cost Range Pwr Mass Notes
Mobile Phone (uses local network) 7/8 150Cr ~5km to tower 1W 0.2  
The Moka 910 is a popular smartphone which is designed to operate on frequency bands and mobile protocols across the Imperium. The ImperialPass tariff allows you to place calls from almost every developed system in the Imperium, routing calls through local cellular or high capacity services. When in jump the Moka 910 seamlessly connects to the ships communications system enabling in-ship calls and information access. The MokaStore has over 10,000 apps available for purchase, and your Moka also doubles as a payment, identity and health management system. Every Moka ships with MokaJi – Moka’s very own digital personal assistant.